I've never gotten this rap on Apple about being 'proprietary.' They DO choose to build their own OS as well as their own hardware.
I guess it's proprietary in that only Microsoft builds Microsoft software and only Dell makes computers that say Dell on them. How is that different? How is it bad?
It IS true that Apple controls the iOS app store and there's certainly some issues with that but it also solves a bunch of problems that Google is beginning to face with the Android Marketplace and the percentage of malware in it.