I have done that in the past, but unfortunately when it's set up that way, it allows players to create tags too--then we end up with bunches of extra incorrect tags floating around to fix instead.

I wish there were a way to make it so players could remove tags from entries without simultaneously be given the option to create new ones (which happens just by tagging something with a typo in the tag), but the way that Dreamwidth's tags permissions are set up doesn't allow for it (LiveJournal's tag permissions used to allow for it).

I will take a look again and see if I can't come up with a better system that allows for players to remove tags from entries.