I agree with wanting jobs to *generally* fit certain aesthetics (though rare exceptions can be cool, e.g. a heavy plate armored white mage) but the idea of everyone being made to do so died long ago.
They're not going to add restrictions to existing gear and start adding unique gear sets for every job to every dungeon. Even if they did, many glamour sets would be impossible to categorize.
Removing the role restrictions from glamour wouldn't significantly hurt the job fantasy given the things that are already possible. It would however make it easier to create outfits that
do fit certain jobs' aesthetics. For example; being able to use maiming-only plate armour on a Paladin, or being able to use certain pieces of scouting gear on a striking job.
These two legs are exactly the same except in different colours and the left one is undyeable. Why shouldn't I be able to use the right one on my Reaper?