When Apple promoted HTML5 as an alternative to Flash, the value was said to be in being an open standard, and in having better efficiency for device-based execution.
The problem is that there are no authoring tools for HTML5. Flash is popular because it’s fairly easy to kick start the creative process. You buy the tools from Adobe for a few hundred dollars and begin to tinker. With HTML5 you need to be a programmer, read arcane documentation, search for sample code and manually integrate results into publishing systems. That’s bush league.
iAd Producer narrows the gap a bit.
The bigger question that I struggled with is whether web apps are competitive enough.