Android is yet another different platform. No real upsides, not really enterprisey and not really secure (at least that's the perception).

availabilty in enterprise is key - can I equip a global workforce with exactly the same hardware? local hardware support? Apple and MS can. Nexus not.

Uhm, really? Surface availability is limited to some countries, so good luck with global rollout. Asus (not Google!) on other hand makes N7 available anywhere.