While I have come to recognize that the Graduale propers are indeed ideal and definitely have the weight of tradition behind them, I'm still not convinced singing the Missal propers is always a bad idea.

If it was indeed the case that the Graduale propers should have been the ones used for singing - in both Latin and the vernacular - it would have been helpful if there were official translations of the Graduale propers from the beginning of vernacular celebration of the Mass. The fact this still has never happened has led me to surmise that the purpose for the creation of the "spoken" Missal propers might have been originally intended for new vernacular musical settings even if that's not what was eventually described per se in the GIRM. (In fact, I seem to remember reading a quote of Bugnini saying that he hoped the new propers were set to music.)

Whether one agrees with the idea of the reform of the Propers or not, that's all water under the bridge. The Graduale propers are indeed often more fitting, and of course they're the texts that come down to us in the treasury of chant. However, there are a handful of occasions where the Missal propers are also quite (possibly moreso) appropriate and are better organized for the calendar than the plan in the Ordo Cantus Missae (here I think of the last days of Advent). I will add that a number of the Missal antiphon texts are not merely random choices but correspond (even with regard to Latin psalter idiosyncracies) to Office antiphons which may be easier to sing by beginning choirs (like those found in the Simplex).

In the end, I'm also confused by how one particular text lends itself to better "understanding" when being spoken vs. being sung? I mean, does a Missal antiphon text suddenly become more difficult to understand if it happens to be sung to a new polyphonic setting? or set in chant (like Fr. Weber's settings)? or chanted to a psalm tone? or chanted recto tono? Does a Graduale text suddenly become more difficult to understand when being spoken? or easier when being chanted recto tono? or when chanted to a psalm tone (like the Chants Abreges)?

I recognize the tradition and benefits of the Graduale propers, and obviously the treasure of their musical settings in the corpus of chant. But do we need to fight a war against the Missal propers?