People its simpler than it seems with the whole MS vs apple debate here:
Apple removes flash support, making their devices less capable, however, they do not have the power to remove flash from the world, since only about 10-15% of website viewing is done from non-flash enabled devices, whether this is laptops or iPads or iPhones etc. The developer community is not going to adjust their ways for such a small percentage of their viewers, and ask of a larger percentage of viewers to update their browsers to HTML5 capable browsers (you know it's true, some people are just too into IE5, especially business end-users).
Microsoft however, ruling a fairly large chunk of browsers, and most people do regularly update to the newest version of IE, reducing it's flash capabilities would be catastrophic for the end user and companies if no replacement is found, so developers would actually have a motive to develop the new technologies, rather than stick with the easier old ways...
I hope I'm making sence here, and please don't downthumb me because you don't understand what i'm saying, read it again!