If we were the only country with a veto I would agree with your assessment but we aren't.
I understand what you are saying, but other UNSC members with a veto can only stop the UN from taking action, they can't stop us from doing what needs doing outside the UN; e.g. Iraq and Kosovo (horrors! a Dem administration acting without UN consent! Doesn't seem to get brought up too often when Bush is castigated for doing the same!)