The mantle of Imperialism has passed to other, bigger nations nowadays, of course, though as for cultural imperialism...  My own feeling is that people like Sting and Paul Simon are not engaging in "world music" as such, but are simply borrowing stylistic traits from other people's traditions in order to feed the hunger of the industrialised world for the exotic, while presenting it in an easily-digestible form.  "Fusion", "Crossover", or what you will.  Similarly, in an ever-contracting world, we have Japanese people playing Irish fiddle tunes, Irish and Scottish musicians trawling African traditions for interesting stuff to play around with... All well and good provided nobody gets too carried away and starts to believe that there's anything particularly authentic about it.  Basically, if you take a few years to learn how to do it properly, it'll sound alright (provided you never try to sing in a language you can't speak), but I'm not sure why you'd want to, unless there's a particular style or form that you have a real passion for.  Not much help, I'm afraid!

Malcolm