All satire (well, at least the best of it) has a ring of truth to it. It's just that with The Onion it's really biting, and really close to home. That's what makes it so good.
The PC's can rant all they want, but the list, while a little bit over-the-top, has that ring of truth. And I don't think the list, or this thread, is racist in the least. We've made fun of silly names and silly people of all races.
"LaTwanda" is no more assinine than "Cheyenne"
The history of slave names, genealogical tidbits, historical references...
Not to mention, it's just plain fun sometimes.