So, in this regard, iOS was released without multitasking which was baked in some versions later. it's not like they only needed to switch the underlying OS features on.
Also: I don't see how this saves battery life if done properly, years before iOS and Android other mobile OS' did multitasking with a similar battery life then the iPhone.
The only point that stands is that Apple (may be) didn't want to confuse users with multiple running apps, but then again.. why did they implement it in the end anyway?
My opinion: It was obvious that the iphone will have multitasking (and copy&paste and wallpapers, and what not) at _some_ point in the future. Imagine Steve's presentations in the coming years (while announcing a new iPhone/iOS version) without those "big improvements". You keep those things hidden to have some new features to throw at your customers. Android just happened to be first on some of those..