Of course it doesn't if it is undermined and criticised at every opportunity in certain quarters.
It's interesting to note the contempt that successive US Republican administrations have for the UN, at least at the beginning of their terms (
link). Of course they would probably argue that their initially antagonistic approach improved the UN in some way which is why their views changed by the time they left office.
Perhaps the reality is that the UN is an essential forum in times where there are few 'local' issues in the international community. Fortunately from the start the Obama administration has taken a far more positive approach (
link).