This is very true, but I think doing it one step at a time is a good way to slip into a more power-efficient system without breaking tons of top apps.

Too many top apps were dependent on constantly waking up and doing network or other expensive jobs. So for M Google says 'these things won't happen when the user leaves the phone on a desk for 30m+' which spurs people to prepare for this new world even if they won't encounter it much. Now with N Google is saying 'this will happen when the screen is off for a few minutes' and now any decent app needs to prepare for this, but the best apps already got into this new world for M.