I think people who are confident in their own body and aware of their size (like, not really overweight) are the people who should wear bikinis. I mean, I don't like when girls put on a little teeny bikini, which ususally looks great on them, and then they wrap themselves in a towel and barely go into the pool. If you're gonna wear it, wear it with confidence! Also, I don't like when people wear really small, tight ones when it clearly doesn't fit. I'm sure they could find ones that do fit, but they don't. There's a girl in my school who is slightly overweight, mostly very top heavy. She posted pictures on Facebook of her in this itsey bitsey bikini which was not flattering in the least bit.
With that said, I'm kind of overweight, and while I might possibly be able to wear a bikini, I don't want to until I lose more weight. Because honestly, I would not at all have the confidence yet, and IMO not the body either.