A dev HAS to support older OS's because he isolates those who don't use the current OS (because of fragmentation) and loses ROI (which is a joke in the Android world). You can't just ostracize an entire group of users when there are so many versions out there. Why even bother developing the app then? For the 0.4% who have GB? Or when the next version comes out for the little bit who have that? A devs goal is to maximize his revenue. Cutting off users is a ridiculous suggestion.