That's a nice ideal, but we both know the vast majority of users aren't up to the task. Especially when so many popular devices are locked down to prevent it. Even those who are capable of dealing with it (such as myself) just don't have the time for it anymore - especially when we have to learn/figure out so much (how to do it, which ROM is going to work - as well as contain the features we want, how to deal with issues that may crop up like app compatibility, hardware that doesn't function properly, etc.) just to accomplish something we're only ever likely to do once in a blue moon. I used to love all the custom ROMs back in the day, but it's become such a headache nowadays for anyone but the most hardcore to deal with.

Which is, of course, exactly how Google wanted things to go.