Android would not have a real fragmentation issue if 70% of all users could easily update and did so within 12 months. Important distinction that negates this argument I think. (I am Android user for day to day phone)
But the fact is that they haven't upgraded, regardless of whether that's due to unwillingness or due to unavailability. Willingness to upgrade doesn't matter if you can't upgrade; you're still stuck on the old version.
