It would be the worst thing imaginable. If humans have proven anything in their history, it is that we can all fail abysmally even with the best of intentions. We need counter-balance and opposition to be even remotely healthy.
*You don't have a soul. You are a Soul. You have a body.
*Faith is the art of holding on to things your reason once accepted, despite your changing moods.
It's a very bad idea because the idea of a political refugee will be extinct. No where to run to except death.
If one is faced with no escape other than death, this will create an indomitable force. There's nothing more potent than a person with nothing to loose. Because of this in our nature, a one world government will not be possible because making people homogeneous isn't possible.
If it is ever possible, it won't be in existence forever.
If Earth to be under one big government, then there must be another planet to run (launch) to. Freedom is very important, the ability to choose.
Think about it, even one government for one country disregards minor groups and minor interests, overlooking many issues of great importance because there is too much on their plate. Bureaucracy would be even more hellish than it is now. And what kind of a government would it be? A representative democracy with a million people in the legislative branch? A dictatorship? That wouldn't last a couple of months with this much diversity. Look at the European Union for example.
Definitely agree with Usehername here. As soon as a group comes along that's significantly different from two opposing groups, the new one is the one to be ostracized. Look at early American history, for example. Irish and Germans were seen as dangerous to established culture. They banded together with an influx of Southern Europeans, and the same happened with immigrants from South America or Asia.
So, without a comparison of sorts to unify us, I think humanity would simply glob into its own self-defined groups. We inherently need to feel different, or at least defined.
Therefore, if the leaders of the NWO know what's good for them, they better start "leaking" information on Area 51. Unite against the extraterrestrial menace!