As long as we are a permanent, veto-wielding member of the UNSC, the UN can do nothing to hamper us. They have no authority over us unless we give it to them. As a standing organization, there are times when the UN can be useful to us, but the beauty of the current charter is that the USA can stop cold any action we don't like--we'll never get that type of power again in any new organization or if the UN is "reformed" by the internationalists.
If we were the only country with a veto I would agree with your assessment but we aren't.