It is kind of funny watching all the wailing and gnashing of teeth over what is a fairly straight forward and sensible business move.
A Run Time Layer (RTL) has significant disadvantages (what the new SDK clause prohibits).
It uses more resources, (both memory and CPU cycles). On a mobile system running a limited processor and limited ram, that alone is significant.
Next though is that it leads to lowest common denominator applications. When you write an application to target 5 platforms using common upper layer and target run time layers, you get applications that are not optimized on any platform. Compare the Adobe Air cross platform App (Reversi) with a typical game on iPhone making efficient use of 3d hardware.
If such RTLs predominate you pretty much lose the ability to innovate your platform as you are at the mercy of the lowest common denominator of all the supported platforms.
Blocking such RTLs is really the only sensible course of action if you want to get the best out of your platform. I would not be the least bit surprised if Microsoft also blocks RTL as well in Win phone 7. I definitely would.
This isn't just about Adobe, it about enforcing development of true native apps which leads to better apps, and more platform innovation, which leads to better apps....
Imagine if instead of native development, console games were developed through an RTL. "Hey great, write once and run on Wii/PS3/Xbox". But if you think about it for more than 2 second you would realize the everything would be limited to the graphics of the Wii, and basic xbox/ps3 style controllers. There would be no incentive to innovate platforms because you are stuck with lowest common denominator cross platform RTL... We would probably still be using PS1 if this was the case.
Native is the only sensible way to go. Apple as usual is about enforcing the sensible.
