Given the non-representative nature of a large portion of the governments represented it can not and should not be given the weight of "speaking for the world.
Then who speaks for the world? Who rearranges the UN, the US? The UN is the closest thing we have on the "pulse" of the world. This is where nations voice their concerns, police them if you will. You don't agree with the UN simply because it doesn't serve your mandate no? Justification for attacking Iraq. Unfortunately another reason why Terror and would be terrorist will never stop, because of these views.
Is there another entity, where by people can voice concerns of the world? Nothing is perfect, including the UN, however bottom line is that the US and UK attacked Iraq against the UN's wishes. The two most powerful nations in the world, thumbs the UN and attacks anyhow. Why?