This DEFINITELY has nothing to do with the fact that Apple pushed down iOS7 forcibly, whether users wanted it or not. Sure, they didn't HAVE to install it, but if it's taking up room that I can't get back, I may as well install it, right?
I called this a few months ago, because Apple always proudly states the amount of adoption its new OS gets. If you force people to upgrade, there will be artificially boosted numbers. The number I would be more interested in is the percentage of people who chose to install it freely, knowing full well what it was going to do. The user reviews for iOS7 on Cnet are abysmal.
Granted, 99 reviews is not a good cross section, but I know a bunch of people who upgraded and dislike many things about iOS7.