I disagree with your points:
a world government would IMO create the following:
1. a group of supper eliteist would control everthing with no respect for culture.
2. all financial/net worth issues would be determined by one group with total disregard for whom created it.
3. organised religion and political diversity (i.e. political activism)as we know it would be in serious jepardy due to the watering down of individual rights.
4. the little people (you and i) would have no say what so ever in the creation and eforcement of laws. just look at what just happened in Iraq.
5. space travel would be a thing of the past, all eforts would be on bringing everyone into equality socialy and financialy thus leaving few resources for technological advancement.
i could go on but sufice it to say, world domination by a single force has been tryed and has failed many times through out history and if attempted now it would fail again.