Because you CAN churn out HTML5 in different text editors (or Dreamweaver) doesn't mean they're a GOOD way to generate rich content.
While I think Flash (the authoring tool) is a bloated mess, it's light years ahead of anything that exists for creating interactive content with HTML5/CSS/Javascript. There are no good tools for generating something like the Wired app in HTML5.
Actually, the Flash Builder app in CS5 can output to Canvas, but unfortunately, the latest version of mobile webkit that renders UIWebViews still has fairly poor Canvas rendering capabilities and performance.
While I think Flash (the authoring tool) is a bloated mess, it's light years ahead of anything that exists for creating interactive content with HTML5/CSS/Javascript. There are no good tools for generating something like the Wired app in HTML5.