Now, if the 'performers' are giving a tune a pop sound, that's their problem, not the tune's. I just can't see rejecting an old melody and theologically unobjectionable words because a modern pop singer got hold of them after the copyright lapsed. "Christian Rock" singers mess with old hymns all the time, that shouldn't cause them to be rejected.
And you can't have it both ways. If the people won't sing because they don't know the music, they sure as heck know "Morning Has Broken", so they ought to sing. And whoever the 'praise band' is can tone it down and let the organ play a simple, reverent accompaniment. It gives the melody a whole different cast.
Now when it comes to actual bad music -- banal pop melodies and words written by worshippers in "The Church of Me", I'm with you all the way. Get 'em out of there.
But let's not confuse our categories.
1. There are bad hymns because they are in and of themselves bad, words and music. Let's get rid of those FIRST -- the "Eagles Wings" and "Here I Am Lord" and all that abominable junk.
2. There are hymns that are objectionable not in and of themselves, but because of various associations - "Morning Has Broken" with Cat Stevens, "A Mighty Fortress" with Luther. Can't do much about the latter since ol' Martin wrote the thing, but rather than rejecting a hymn just because some person of questionable morals or religious views performed it, perhaps a change in setting or presentation would be adequate.
3. Obviously, Protestant hymns with words that are problematic for Catholics should go. "Amazing Grace" is one of the worst offenders, but there are plenty of others. I've heard some astoundingly Baptist hymns in church . . . and a bunch of Wesley (the Methodist Brothers) stuff too.
We need to prioritize, though. My personal preference in hymns is for the old stuff out of the early German hymnals, preferably with translations by Catherine Winkworth, who was a genius in turning German into English without missing either the rhymes, the rhythm, or the meaning, or the good old Anglican standbys out of "Hymns A&M", which generally present no theological problems.
But we've got a long way to go before we start picking and choosing among the hymns that are (1) good melodies; (2) good words. I'll wait!
>>It isn’t pop.<<
You may know the history of that song, Pete in the Pew thinks Cat Stevens. To me, to my fellow parishioners, it’s pop, no matter where it came from.
AND it is not appropriate for the liturgy. While you may not find any of the words to be anti-Catholic, we are at Holy Mass for a reason.