I can see why some birds will pluck feathers in the wild to build nests, however other than I'm not *entirely* convinced that wild parrots pluck their feathers just based on these photos.
I guess it depends what birds you consider *wild*. If I'm not mistaken those Mitred Conures are the feral parrots that live in California. Some of them were supposedly released but the bottom line is that they're not in their natural habitat so I wouldn't use the plucking of those birds as true evidence.
I've seen some photos of some wild Cockatoos with feather loss, however the feather loss was determined to be from Psittacine Beak and Feather Disease. Usually it's disease that causes feather loss in wild populations.
Maybe there are rare cases of parrots plucking their feathers in the wild but there are a HUGE amount of parrots in captivity that exhibit feather destructive behaviour. Weather the reason for it is medical, physical, or behaviour it almost always comes down to the fact that the in one way or another the feather destructive behaviour was caused from living in a captive environment.
That's just my opinion but I'm definitely open to hearing other opinions and seeing other evidence as well.