This sounds good, but it sounds good in the way that Socialism sounds good. When actually put into action, the idea wouldn't turn out as well as it was supposed to. Just because an area on the other side of the world is having economic trouble, I really wouldn't like to share in their problems. Sure, people should help them, but the way to get people to help isn't to throw them into the trouble as well. On the other hand, I am not selfish enough to think that just because my area is having trouble, the rest of the world should suffer, too.

No, because one worldwide government would ignore the diversity and the differences in cultures throughout the world. The reason that governments are separated into countries is mainly due to the differences in people and what they expect from their government.

Even if a government was to try and incorporate the diversity of the world into their system, it would be a massive bureaucratic behemoth. Even governments of countries today cannot meet the needs of the different people that make up their country.