Devs can still have all the power, as long as excessive battery usage is more transparent to users. I'm not sure about iPhone, but OS X has an indicator with "Apps Using Significant Energy." [1] as well as a more detailed breakdown [2]. Very useful. Often turns out to be a stray tab in Chrome. Would like to see something like that.

[1] http://support.apple.com/en-us/HT5873

[2] http://support.apple.com/library/content/dam/edam/applecare/...