I have the choice of buying a completely controllable android device if I want to install mystery apps willy-nilly. I'm not interested in that, and there are millions like me. I want a locked-down device that keeps developers in check.
This situation is much like the browser nightmares of the past, where Firefox users complained that the browser was slow. People didn't really take into account that the slowness wasn't fault of Firefox, but of the zillion janky browser extensions people freely installed. Chrome came along, and people were wowed by how fast it was, not realizing it was 'fast' because they hadn't installed 47 browser extensions yet. Apple doesn't want to be Firefox, and I don't blame them.
I want my phone to be like a Nintendo, I don't really care about the freedom to install any random code I download (even though I really could if I wanted to install something I built locally with XCode). First and foremost I want developers to be terrified of getting their publishing privileges yanked if they step out of line.