Looking at the SL forums, "Barbie" appears to be quite the insult. (For that matter, I guess it is in RL, too.)
One school of thought appears to be that because you can control your appearance in SL, it's reasonable to judge you by it. That strikes me as uncomfortably close to "She was asking for it by the way she dressed."
I'm torn. I would like to avoid being judged a "Barbie"... but I like being tall and slender, and having long legs, and—let's be honest!—large breasts, and in SL, I can. I revel in it! I don't think I should have to apologize for that. On the other hand, there's not a single official beautiful body shape, and I've seen a wide variety of beautiful or handsome people in SL, even if they don't think of themselves that way (*cough* Mordecai *cough*). Thank goodness.
Actually, I wonder whether imperfections will become prized in SL, like tea ceremony vessels that contain intentional deviations from "perfect" form or symmetry?
(Now, of course, I'll start second guessing myself about blog posts, and worrying about whether I'm just showing off in choices of example or reference—"Ha! A Barbie wouldn't mention the Problem of Evil, now would she?" But that way lies paralysis and self-censorship, and I do enough of that in RL. Must not go that way.)
So...dust off your IDIC and wear it proudly. Can't we all just get along?