Remember how character creation is limited in its depth? Can't make characters that don't look like they fit within the lore and game world?
Same point here. The Glamour system has to make sense.
Edit:
Though yes, I do understand the problem with the current gear system, especially the 'All Classes' gear and the ability for tanks to wear nearly all gear while casters are heavily restricted.
Still, that's something they need to fix, and is no excuse to remove restrictions from the Glamour system.