LOL! It's not that the UN is imperfect. You might as well use that defense for Saddam. (You can't expect a dictator to be perfect!) The problem is that the UN is a failure in every part of their function outside of giving (mostly Western) aid. The problem is that the UN is seen as an avenue for resolving problems, when it has to do so even once. The problem is that the UN promotes a Progressive idyll (as evidenced by America's shouldering of the lion's share of the burdens). The problem is that every dictator, despot, and oppressive ruling junta has the same authority as proven peaceful democracies. The problem is that it is depresingly common for the despots to outvote the nations that promote the rights of humans in many important ways. The problem is that UN officials feel that they are above the laws of NY, which promotes the idea of a tiered or stratified system where the rules are different for those entrusted with authority. The problem is that the UN fails to use the guidance of proven liberating and just nations, and forces the leadership positions into the hands of those who represent despotic, inept, or corrupt nations. The problem is that the UN has become a clearing-house for all those nations who want to see the failure of the US, simply because the US is on top and they are not. The problem is that the UN is trying to resurrect a failed ideology (Socialism) to usurp a successful one (capitalism coupled with individual freedoms).
The problem is that the UN is seen as an avenue for resolving problems, when it has YET to do so even once.