Whilst agreeing with some of what you're saying I'm going to pick you up on the "multiple licenses needed on Android" comment. There's only two occasions where I've found that to be the case:
1. Where there's separate "phone" and "tablet" editions of an app - in my case BeyondPod and SwiftKey;
2. Where an app appears to be locked to a particular device - and the only app I've come across that does that is CoPilot (it needs a separate "activation" step - which is a pain)
The rest of the time, as long as you use the same gmail.com account on phone and tablet then you can install on both. Same deal with Amazon's app store - in fact I had one or two apps installed on three devices - one phone and two tablets. Although I've now "rationalised" that.
Being able to "float" a license between iOS, Android and Windows - where an app WAS cross-platform - would be great though. E.g. if I defect to Windows Phone next year then I'm going to have to rebuy CoPilot, and it's not that cheap (comparatively).