fragmentation dude… which startup can shows off with an android app ? As someone could come up with an average android device, with the app runnning slow, being laggy, giving a poor experience ?

you're at least pretty sure your prototype will be accurate when developing for iOS — e.g. you do your job, then let those android developers devaluate it. You take a risk telling people you animations will be that smooth on "android"

Lost my iPhone some weeks ago, bought an android to give it a try… not the best one, not a bad one. But globally, the UX feels so fragile.

It's like flash vs. the web before the mobile era. No agencies/designers would sell an html website, never, ever. You would be laught at by the 90% market share of IE8 users. But this 90% market share would still pay a lot for your glittering flash one