I don't mind Apple being a little bit restrictive, at least not for my phone. I like that they try to vet apps before letting them on my phone because I don't want just anyone getting access to my contact list, GPS coordinates, or image library.
Why is that Apple's responsibility? You can prevent all those things yourself by simply not installing applications you don't trust.
Apple's sole responsibility is to eliminate security holes in their own products that would let someone destroy, modify or retrieve your data without your explicit approval. These nasty things can happen whether or not they refuse to let you use your own device as you see fit.
Experience has shown, over and over again, that security through obscurity just doesn't work. Neither does handing over responsibility for your security to an entity whose interests differ from yours. When the source code for a popular program is available for public inspection, bugs and security holes are quickly noticed, reported and fixed by other users, often before ever being exploited.
Keeping source code proprietary doesn't keep the bad guys from finding and exploiting security holes, but it does keep everyone but the owner from fixing them. There are
many instances of software companies flatly denying security problems with their products until (and sometimes even after) they are widely exploited, and you're helpless until they deign to fix them.
Historically, MacOSX has been much more secure than Windows because it was based on an open source operating system, BSD UNIX. But with iOS, Apple is succumbing to full-blown Microsoft-itis, and we're starting to see the same kinds of problems with their stuff. Did you hear about the journalist who had all the data on all of his Apple devices wiped clean because someone who didn't like him called up Apple, pretended to be him, and reported them stolen?