On the other hand, if Android supported IA_NA we would probably be seeing ISPs in the wild handing out /112s and going "But it's 2^16 IPs! We're being so generous, what could you possibly have to complain about?", so it's quite possible that adding support would be to the detriment of all Internet users.

Android does now support IA_PD, so the people who need to track IP use via DHCPv6 requests should now be happy. (We'll just put aside the question of whether doing that even makes sense in a world where devices can be told to use any IP.)