There are some very nice and perfectly acceptable protestant hymns, but they really do not belong in catholic liturgy. for 100 years and more, popes have been asking Catholics to sing the mass itself. Most Catholics don't know that there are music settings for every day of the year, and that the mass is intended to be sung. Even if most people don't have the time or talent to master separate chents for every occasion, we can all learn the ordinary parts: Gloria, Credo, etc.
Hymns are really an intrusion on liturgy, and their over-use reflects the widespread rejection of Vatican II's call for Gregorian chant to enjoy pride of place in Catholic worship.
I'm a convert from the Presbyterian church, so that perspective doesn't really resonate with me, although I'm sure you're correct. As with everything that I don't, personally, "get," if the Pope and Bishops say, "This is what you'll do," then that's what we'll do, with as little grumbling as possible.
We had a guest priest yesterday, representing "Food for the Poor," and he mentioned that his parish in Idaho has a Swahili service, in which the African congregation sings the entire Mass.