It's difficult to say. So many different cultures and economies would be difficult to link. Let's just say for sake of argument that a world government could work; that the People were significantly united behind it, and a strong democratic Republic could be constructed. I would be tempted to support it. Though in likelihood not, because of the immense danger corruption would mean for us all. But if we didn't have to worry about that and go on some ideal, like the Federation from your Star Trek program, then I can see real advantage to having one. Uniting the whole of humanity could bring about significant progress.