Re: Running in the background
"..but continue to play music.."
Besides, the usual iPhone users generally press Home button to get out of the app and forget about it. So, at a time, a general user has 20 (i have seen 30) apps in the background ready to be resumed (that you can see by the double tapping the Home button). This is supposed to be efficient because these background apps are not allotted CPUs until they come in foreground.
So, what this result seems to be is about apps which perhaps have a special permission to run (consume CPU) in the background.
If Apple is allowing such apps (which go against the users' habits) and is failing to scrutinize them thoroughly (scanning the API usage), then it is the same problem that the other stores are blamed for,