Except that Apple is actually a hardware company, not a software company. They produce and sell software to make their hardware more appealing. Not sure I can see a reason why they should produce a tool to turn Flash into HTML. I'm sure they'd do a good job, but wouldn't it be better to leave it to those who build those kinds of tools?
Apple makes software to help mousse their hardware sales. This is a case of putting your money where your mouth is. They want HTML5 adoption because it would help push their hardware, they need to make it a viable platform by providing tools.
Thinking like you do, we wouldn't have Xcode and Interface builder. Hey, Apple is not in the business of making developer tools, wouldn't it be better to leave it to those who build those kinds of tools ?
It's easy to play armchair quarterback.