HTML is designed for more or less static content, but the DOM itself seems well adapted for dynamic content. Since it comes out of a tradition of streaming over slow connections, it's made to be dynamically rendered. The content layout is flexible and somewhat intuitive.

Compared to something like Swing or Cocoa, the only drawback seems to be the paucity of widgets -- we basically just have basic inputs and scroll bars, the rest is app-specific. But that also brings a certain flexibility. I think an update to the table element would be great, perhaps with support for streaming data and more flexible layout.