Any sort of world government is colonialism by another name. The details of the structure would only affect who is colonized and who are the colonizers. The current system is far from perfect but it is really the only option on the table.
Bullshit! If you look up the meaning of the word colonialism you would find we have been practicing it for decades. How many times have we gone into a poorer country, stripped out the natural resources and said syanora? World government, if managed properly could reweave that and give people a fairer shake.