So... Normally, I would collect some data on how many tags are created by users at various rep levels, and how they were used. This is a pretty decent way to gauge whether anything of value would be lost if the privilege were bumped up.
I started to do that here. The results looked good - barely any tags created by low-rep users, a slam-dunk status-completed. Then I ran the numbers on tags created by high-rep users, and things got weird: they weren't creating very many tags either; in fact, I counted only 87 tags created here during the last year by anyone. That seemed... Odd. So I went to do the last check: how many tags were destroyed during this time-period.
I found that only a hundred or so had been destroyed by the system due to low/no use. However... In the past couple weeks, over 1400 tags have been merged, mostly into this big ball of mud.
That... Pretty much makes doing any further analysis right now worthless. It'd be really nice if we tracked information on deleted tags, such as who created them and so on... But we don't.
All I know is that of the extant tags created during the past year, there's not a very significant split between low-rep and high-rep users; the only new tag to garner more than a few questions did so via merges and will be destroyed itself - if new tags must be created in the process, that will only skew this analysis further.
Marking this status-deferred - please get rid of this tag as quickly as possible, and then remind me to check again in another few months to see who is actually creating useful tags here.
###Update
Over a month later, that tag was still around. So I've removed it with extreme prejudice. There is some cleanup to do in a tag that cannot be added to new questions or ignored when editing old.
I will revisit the tag-creation privilege in approximately six months, by which time we should have sufficient evidence of need.