Chicken -- many of the propers (introit, et al) are the words of Jesus. It's more common in the OF, but there were some good examples in the EF:
"Tu es Petrus"
"Simon Joannis, diligis me plus his?"
"Dico vobis: gaudium"
"Pater, si non potest"
Several ones starting "Dicit Dominus" or "Ait Dominus".
The improperiums
Lots and lots of stuff during Holy Week and Passion Week
And so on. Which is to say that you're mostly right, but that there always has been a lot more of this sort of thing in Catholic music than you're thinking.

keep patient...the tide is turning.

Don't it make your brown eyes blue? How in the world do these guys think they're relevant? It's just goof ballitis.

When the words of Jesus are quoted directly for four verses and a refrain, the congregation is obviously suppposed to recognize who is the speaker.
They are singing a referential song simply speaking as Christ. The only time I know of when this was done in liturgical practice was in Liturgical Dramas, such as the Play of Daniel, which were adopted from eleborate pre-Introit plays.
It is true that certain portions of Scripture show up that may be incorporated into the Liturgy for certain feasts, such as the Magnificat, but setting where the words of Christ are song is most often done in extra-Liturgical settings, such as Bach's Passion setting.
It may be blasphemous, if it is intrinsically so for the congregation to speak the words of Jesus
They are singing a Gospel passage during Mass. A priest may do this, but not the congregation, usually. Imagine that the song were done in plainchant. It might make the violation more obvious.
The Chicken

We have a priest who during the creed says "For us [pause] and our salvation". Half the congregation isn't sure what to do, so it ends up being "For us [mumble] and our salvation".
I was going to call this genderphobia and then looked it up to see if it was even a word. Interesting that it seems to be a slang term defined not as the fear of gender, but as the fear of people who fear their own gender (cross-dressers, transsexuals, etc).

"For people to speak as God is an implicit form of Blasphemy, unless one is speaking in persona Christi as the priest does at Mass . . . nowhere in the song does it say (unlike in St. John's Gospel), that is is Jesus who is talking. It simply says, 'I am the Bread of Life...' Does that mean the singer?"
No, of course it doesn't. When the words of Jesus are quoted directly for four verses and a refrain, the congregation is obviously suppposed to recognize who is the speaker. There are hymns, such as the one I quoted above ("Bread of Life" by Rory Cooney), where the application of "I am the bread of life" is transferred to the singer, and these hymns (or at least that one) are indeed blasphemous. It is risible to suggest that Suzanne Toolan's "I Am the Bread of Life" (lyrics) does the same thing. It may be blasphemous, if it is intrinsically so for the congregation to speak the words of Jesus, but in a different way, for a different reason, and in a much smaller degree, trivial by comparison. To say otherwise is to equate what is at most a small indiscretion with a deliberate assault on the doctrine that is the foundation of the Faith.
"It also has the quality of a feel-good song, expressing a veiled notion that anyone who comes to God will be raised up regardless of state of grace, whereas the Bread of Life Discourse was a challenge to the disciples."
I don't find this convincing. The song, just like its source material, is very clear that you will have eternal life if you believe in Jesus and eat his flesh and drink his blood, and will not if you don't. Where do you find this "veiled notion"? Or rather, what portion of the Bread of Life discourse should have been retained in the song to avoid giving this impression?
"Finally, some versions use inclusive language and further muddle the ideas."
That is not an argument against the song itself. A great many wonderful hymns have been castrated, so to speak, in this way. Should we avoid any hymn that has ever come under an inclusiver's knife? Abusus non tollit usum.

I think you were at my parish, except that is our usual priest. (We will be graced with a visiting priest this weekend, praise be to God.) Our priest opened the homily with some New Age story about how a King built a castle with many doors to the throne room, invited all the people and the gate-keeper instructed the people, "There are many ways to the King." It went down hill from there.

A proper rendering of the Latin could be "Dominus estis vobiscum."
Umm, no it wouldn't, since "estis" is the second person plural (you [all] are) form of the verb "esse". Do you mean "est"?
But more directly to your point, the mood of the implied verb is derived from context. Look at parallel uses of the pax/dominus vobiscum in the Vulgate NT and you find that the "full form" of the greeting uses the subjunctive. For example 2 Thess. 3:16: "Dominus sit cum omnibus vobis" ("May the Lord be with all of you"); 2 Cor. 13.13: "Gratia Domini nostri Iesu Christi, et Charitas Dei, et communicatio Sancti Spiritus sit cum omnibus vobis" ("the grace of our lord Jesus Christ, the love of God and the communion of the Holy Spirit be with all of you")

Hmmm…I like “I Am the Bread of Life”, and its original version is not gender edited. Is there anything wrong with quoting Jesus for extended passages?
Pachy, the words are a setting from Martin Luther of the Bread of Life Discourse by Susan Toolan, if memory serves.
The music is catchy, but there are several problems with the setting. First off, it is not a hymn, lifting of the heart and mind to God. It is not sung to God. It is not a song of praise. It is song to the people, the congregation channel Jesus, if you will. I know of no form of worship music in history where that has been done outside of the psalms, which, even then, always has a form of man appealing to God, not the other way around. For people to speak as God is an implicit form of Blasphemy, unless one is speaking in persona Christi as the priest does at Mass. Singing Gospel passages at Mass simply isn't done by the congregation. It has no provenance in Tradition, either liturgically or musically. Quoting Scripture in this fashion is a relatively modern idea (as in after Vatican II).
Also, the words are never identified as being Christ's. Context does matter, but nowhere in the song does it say (unlike in St. John's Gospel), that is is Jesus who is talking. It simply says, "I am the Bread of Life..." Does that mean the singer? If each singer is the bread of life, the there are multiple Breads of Life. Does the song mean to imply that we are the Bread of Life? Does it mean that we are one body, the Bread of life, united in Christ? Does it mean to refer to St. Paul idea of the bread, though scatter is one bread. The referential aspects the song are vague.
It also has the quality of a feel-good song, expressing a veiled notion that anyone who comes to God will be raised up regardless of state of grace, whereas the Bread of Life Discourse was a challenge to the disciples.
Finally, some versions use inclusive language and further muddle the ideas.

One other thing, theologically God is always with us, it is his desire. When we sin we simply choose to ignore him, but it doesn't stop his presence from being there giving us grace and desiring us to use it.
Not really true. One cannot use supernatural grace (except the grace of repentance) when on is in mortal sin. One retains the use of actual graces. Just because God desires to be with us does not mean that he does not respect our desire not to be with him. God is at the center of the soul of every baptized person, but those in mortal sin have placed themselves so far away from God and his light and his friendship are not communicated to them. They are in darkness and alone (in a sense).
Also, as Jimmy points out, theologically, there are many senses of the words "is with us" when applied to God, so when one says that, "God is with us," the correct response is: How so?.
The Chicken

You know in the 5th century this would have led to riots in the streets. Good times! :)

I hear you, Jimmy! At our parish, the music director/cantor always gender-edits the Gloria, and it grates on my nerves. I sing "His" anyway. Our priest does not change any part of the rest of the Mass, (thank You, Lord) and his homilies are usually excellent, for which I am grateful. However, last Sunday, there was a dissident deacon who did the homily. He concentrated more on what we are supposed to do to be saved, which, according to him, means to love God and neighbor and help the poor. He never defines "love God", or mentions "believe and be baptized" or, heaven forbid, "REPENT and be baptized"! It was this kind of social-gospel only preaching that made my husband and I reluctant to convert to Catholicism, not to mention dissidents like Father Gender-Edit and the priest who doesn't like to be called "Father" who was mentioned in one of the comments on the NCR page.

One other thing, theologically God is always with us, it is his desire. When we sin we simply choose to ignore him, but it doesn't stop his presence from being there giving us grace and desiring us to use it.

Why are you assuming that "Dominus vobiscum" should always be rendered as "Dominus sitis vobiscum"? Also even with the Latin subjunctive in an independent clause it can have an element of obligation. A proper rendering of the Latin could be "Dominus estis vobiscum." I think there are more important things to be concerned with.

Cross-posting of comment left at the NCRegister page:
Hmmm…I like “I Am the Bread of Life”, and its original version is not gender edited. Is there anything wrong with quoting Jesus for extended passages? At the very least, if it is a problem, it’s a very minor one compared to hymns like the one that goes “I myself am the bread of life, you and I the bread of life” etc. That’s downright blasphemous.