Just potentially throw away hundreds or thousands of dollars in purchases for apps/IAPs and related things! FFS there isn't even a way to watch videos purchased on iTunes on Android so if I want to watch my copy of Futurama on a phone, it has to be an iPhone ( and for those in the U.S, "Movies Anywhere" doesn't exist outside it and I have no idea if that even applies to TV).
Sort of. One can use an alternate store on Android. Otherwise I would see google in the same boat. Apple could allow such side-loading but I kinda get the feeling they don't want to take the revenue hit. (I know arguments appealing to user security; it's hard to ignore the convenience of these arguments with regard to them retaining revenue.)