OK, great; so what is the difference between Missal antiphons and ?Graduale Romanum? antiphons? thanks

The GR contains the true, ancient, and historical propers of the mass. These antiphons and responories, five of them for every feast, are the true propers. They are always permitted as one of several options laid out in the GIRM. The mere two antiphons in the Roman missal are for the priest to say when there is no music. This hasn't stopped some from setting them to music, publishing them, and calling them 'propers'.

chonak - I know we go round this loop repeatedly, but :
"were intended" is (always) incomplete without knowing who intended it. Bugnini says "The entrance and communion antiphons of the Missal were intended to be recited, not sung, and to inspire the composition of suitable songs in the vernacular " Reform p.891
The purpose of the distinction about a Missa lecta is evidently the preservation of the ancient Gregorian chants from any neo-gregorian innovations in Latin. The Apostolic Constitution does not even mention the Graduale Simplex. Any vernacular translation of the Missal involves some adaptation, and Paul VI recognizes that :

While leaving room in the new Missal, ..., "for legitimate variations and adaptations,"

Most of the inventiveness went into "Ordinary Time", where of course there were new readings to be matched. And a lot of that into ferial weekdays where it has little chance of being sung, though Fr Weber seems to have provided for every eventuality, on the web.
As to GS, it could have played a very useful role in stemming the tide of polluting rubbish, had opposition, and timing of calendar revisions, not derailed it, IMHO.

Lettest thou not the enemy of the good the perfect be. (Or wordes to that effect.)

Unfortunately, many of us are not bless'd to be in the milieu of the Latin Extraordinary Form or the Ordinariate, and must make do with what we have---which includes pastors. Latin in many places is all but verboten, and it can take years for The Powers that Be to acquiesce to a simple Communion Antiphon, and that under the stipulation that it be in English, and match one of the Options in the Missalettes. While I agree with you that the Graduale Propers are better, the Missal Antiphon chanted even to a psalm-tone (like in the St. Peter Gradual) is better than nothing at all.

Also, in the Ordinary Form we have 60+ years of "The Music Must Match the 'Theme' of the Lectionary" baggage that has to be stripped away before certain things are welcomed. Nearly every Catholic Hymnal that I have seen, with very few exceptions--like the Adoremus--have an index of hymns cross referenced to particular Sundays, not just a scriptural index, so that the Hymns can "Match the Readings". The Ordinary Form wing of the Church is, in the main, hardly ready for the chanting of the Missal's Communion Antiphon "The Word became Flesh and dwelt among us" at Midnight Mass, let alone the Gradual "Tecum principium" for the same or, heaven forbid, "Vir erat"--the Job offertory--on Ordinary Time XXVII. There is also a bias against "Ye Olde Englishe" that needs to be dealt with, too. I once had a parishioner register an objection to (wait for it!) "Immaculate Mary, thy praises we sing, Who reignest in splendor with Jesus our King" because: 'People don't talk like that'.

As much as I wish it were n't so, One cannot simply foist The Plainchant Gradual on an unsuspecting Novus Ordo Parish. The people would be more revolting than they already are. (Or something like that.)

Let us not elevate the Propers so high, though, that one would prefer their text sung recto tono or to a psalm tone (destroying the balance of text and music so intrinsic to the idiom) to a real, musical, and textually apt composition that is not necessarily prescribed. The Proper texts themselves are nothing special - it is their union with supreme and unique melodies, above all the melismatic Gregorian repertoire, that grants them perennial status. Let us settle for nothing less.

I would far rather hear Howells' A spotless rose at Christmas than some half-hearted recto tono rendition of Laetentur coeli, superior though the Gregorian melody would be to both (though I would never want to live without Howells). In my view, robbing the texts of their unique context just to have them "sung" in some way, shape, or form is pure rubricism and will likely be received horribly by those individuals opposed to Propers in the first place.

I echo Jackson's desire to see collections in a properly modern (no pun intended) idiom.

I should qualify my remarks. As texts, the Propers are wonderful, luminous selections, uniquely apt for the weekly cycle. However, specifically musical selections in the Mass cannot solely rest on the text to carry an otherwise unrelated musical form like a psalm tone or recto tono. Compare the relatively simple tones for the Lectionary readings to the ornate tones for the shorter Proper texts, a very specific, intended, and appropriate difference in setting. To mix and match these forms because the Proper chant for the day is "too difficult" or any other excuse does a dis-service to the very idea of musical Propers and amounts to pure legalism in many circumstances. That is what I meant by the texts being "nothing special" - in and of themselves, they neither save an inappropriate musical form (witness the OCP Antiphons collection of late) nor, without the union of an admirable musical setting, are what the Church really intends or deserves.

Spoken/recited Propers are a different matter entirely as the musical aspect is entirely absent, and they can stand in their own right as majestic and uniquely suited readings.