Something tells me it's more to do with adequate hardware capabilities and sufficient libraries. While Android is near 70% of the market, there is just so much diversity... Kind of like PCs, but now you have a choice of 30 different OSs to pick and like 100 different GPU architectures (exaggerated).
Also, I just noticed from that screenshot that they are using the cover system from XCOM (the half and full shield icons).
I'm sure it'll come to Android at some point. If I were a developer I think I'd develop for iOS first also, just because there are far fewer devices to worry about. Just look at reviews on apps over at Google's Play Store and you can begin to see how experiences can change for people based on their device. It must be a real headache for an Android game developer.