well, technically you're not supposed to use a bandages on a cut, prevents it from breathing, and healing quickly. If you're talking about those huge cloth things that wrap around, or casts for bad breaks, then that's to keep people from moving the limb and making it easier for the bone to heal in it's proper place. If you're talking about what Raislin847 said, putting them inside the body instead of outside, yes they do do that, but not with bandages, they use other things I believe.
Uhuh, I think he means the big ones. Those are for what Raptor said, also, if you haven't noticed about the little bandages, THEY HAVE HOLES IN THEM. So they do let it from breathing. [Well, a bit more technical than that, but you get where I'm getting at]
Guys, last time I went to the doctor with a broken leg, he gave me a Hello Kitty band-aid and a glass of chocolate milk, and the next day I WAZ ALL BETTR!