it is easier to keep it clean i suppose.
Is it really that hard to just pull the darn foreskin back and wash? I imagine it's no different than cleaning the weird folds in your ear that get dried shampoo caked up in them -- but we don't remove those.
As for the OP, from what I've heard, it has to do with a few factors.
1) It's an extra source of money for the doctors.
2) It supposedly makes little boys less likely to wack off.
3) It looks "normal," which is a reason that only exists because of the first two.
I think something is fishy when you see medical associations all around Canada and Europe saying circumcision is unnecessary, while American medical associations insist that it is.