I'm hesitant.
First of all, as a minor point, "rarity" doesn't cut it as a measurement. Immediately, I think of Planescape, where tieflings (but not 4e tieflings) were common, and halflings and elves were rarer. Or Dark Sun where gnomes aren't just uncommon, they're nonexistent. I am not sure that, in a modular game, the designers should worry too much about defining how "common" different races are in a default assumption.
That's a minor point because it's mostly a word-choice issue. The major point runs a little deeper and it is this: not every race belongs in every setting. If you have Race X in the core books, it is very, very hard to take it out in a given setting. Eladrin in 4e Dark Sun exemplify this for me, since it's a race that clearly doesn't fit the melieu, being put into it, simply because it was part of the core.
That's a bit more of an insidious thing, because it's not always obvious until you're designing the next setting that you need to find some way to shoehorn a given race in.
That's avoidable, of course, but it takes some guts to do it.
Personally, I think a much more useful division of races is the amazing power of
tropes. Give a "default" (Hero = Human, Lancer = Half-Orc, Smart Guy = High Elf, Big Guy = Dwarf, Chick = Halfling), and some swaps (Big Guy or Heroes could be Dragonborn! Lancer could be Wood Elf or Halfling or Gnome! Smart Guy could be Gnomes!).
Probably not horrible either way, and I absolutely think these guys have a role to play in the game, but if you put Dragonborn into the PHB and the proceed to cram them into every setting orifice you produce, regardless of their suitability, you have a problem.