Good lord... if my gamers brought the same level of "OMG NO!1!!!11!" to the table as some people bring to these 5E threads, I'd be tidying up my nice new digs in the state penitentiary.
Try to look at "common, uncommon, rare" from a different perspective. These labels don't have to tell you how common or rare they should be in
your game. Think of them as an indication of how often they appeared in the various editions of the game--without having to put a definitive edition label on them, which would probably keep the edition warfires smoldering.
(I can imagine there exist a few edition zealots out there who'd be ecstatic to see WoTC categorize the game elements with literal edition labels so they can more easily recognize those parts of the game that have anything to do with those vile and hated editions which could potentially corrupt their delicate sensibilities through inadvertently reading
the mechanics that shall not be read)
"Common, uncommon, rare" works perfectly fine if you think about them from an
all editions encompassing frame of reference.
Did it exist in all editions, pow, common.
Did it exist in two or more editions, bang, uncommon.
Did it exist in only one edition, bam, rare.
Could WoTC use other labels? Indeed they can and perhaps should--judging from some of the reactions in this thread. Having them categorized is still a great idea and offers a straightforward method for a DM to allow or disallow races/classes/whatever.
You could tell your players:
"Feel free to use any
common or
uncommon elements to create your character before the game on Sunday, contact me if their is a
rare element you'd like to explore and I'll think about it."
Or,
"Feel free to use any
common race, except those horrible halflings! Gnomes and half-orcs are okay, but no other
uncommon. Oh, and don't even contemplate any of those weird
rare races, unless your dragborn is sans the mammaries."
You can even change the category of an element if you want:
"Drow are
common, they're like dog poop in my campaign."
At the end of the day, you can still just list straight out what you want to include or leave out, and completely ignore the labels with no additional work required (save what you'd have done in any previous edition by writing out the list of races/classes/whatever).
The categories are there to make things easier and should have absolutely no game mechanic associations, so they don't actually matter if you totally ignore them.
