I think this might be slightly over-stating the problems globals cause. Well we should certainly try to decrease their presence, I don't think they're preventing newbies from contributing, or causing huge problems in developing mediawiki (although they might affect tests more than normal development).
Personally, I don't see that much of a difference between a global like $wgOut that is pretty much the only instance of its respective class and a static method to get an instance of the class to be used with the request ( RequestContext::getMain()->getOutput() or whatever)
(Of course things like $wgTitle is just evil and needs to die, but that goes without saying ;)