I agree with you, and the peace keepers there deserve much of the blame. But the UN did eventually get Milosevic, and that part is good. Nothing excuses what was allowed to happen with the massacre of civilians, and that's a big mark of shame for them. But writing off the UN because of this doesn't make sense, especially when the U.S. record isn't by any means perfect, not just in preventing massacres but in supporting those that carry out massacres, and in Panama killing and trying to hide the deaths of many civilians. I think the point I want to make, is that warts and all, the UN can accomplish worthwhile things.
It would be way too expensive to provide government services to all these countries. Hell, if the US conquered Iraq and they all became American citizens they'd probably just come over here.