Sounds like another way for apps to drain my precious battery life.
Given about 90%+ of mobile users have access to a wifi point + charger on a nightly basis, this seems reasonable.
I'd mainly use it for podcasts and Audible - keep my casts and books updated so I don't have to sit in the car for 5min downloading the daily selections.
That said I also played a ton of the radio last month too but I wish I could turn 3g for the radio stuff and not the rest instead of toggling it all the time.