Anyone who lived with the Mac classic environment for a while can tell you that managed memory is nice. In practice, the segfaults never all get fixed.
It was especially awful when the segfaults were my own, because I'd have to reboot the computer 50 times a day when writing and testing my own code. Development became oh-so-much-nicer when I switched to Linux, and I just got the "Segfault" on the command line rather than "beep-reboot." Either way I fixed the problem, but with Linux I didn't spend half the day waiting for the computer to come up.
It's a bit different with power management. In a way, I think policy might be even more important in this case: the developer may not notice or immediately suffer from power management problems in the same way that the developer him/herself suffers from memory errors. So the incentive of someone who has just developed some mobile app to fix the problem may not be as high as you'd like. Do you really want to spend your whole life acting as a cop and beating on people to fix their code? There's not enough time for code review as it is.