Cage vs. Shield?

So, I'm on record opposing the half-shield; it's a good way to get your jaw broken, lose a tooth, or even get a nasty eye wound. It's better than nothing, but worse than reason. Anyway, that's not the point. I was watching some of the NCAA hockey tournament and I got to thinking, what ever happened to the full shield? That's what all the college players wore back in the early 90s. The cage was considered old and clunky. Now you rarely see a full shield, and the college kids are all back to the cage. What happened there?