Most of the faults of colonialism seem to come from how poorly the handoff between the imperial powers and the local population went. It's an interesting dynamic, since almost all of the traditional colonial powers were a shell of themselves by 1945, while the two ascendant powers were the USA and USSR, who really hadn't been involved in the Victorian era colonial land-grabs, at least to the extent that the UK, France, Germany, Belgium, and even Italy were.
