You've hit on a pet peve for me! In 20 + years of boating, I have never seen a facemask catch, nor had mine snag. I have had my vest catch on a submerged branch and tear. I guess we shouldn't wear vests now because of potential for snags?
If it saves you a blow to a temple, or broken teeth or stitches once, it is worth the hassle factor in my opinion.