Okay, not HTML per se, but HTML when it applies to eBooks.
HTML for web sites? Brilliant idea, and even it if it wasn’t, I’m not going to suggest changing it now.
But when the idea of eBooks was first floated, we had a completely clean slate; we could have gone anywhere, done anything. Instead, we plumped for a technology that had already shown how difficult it is to get the same look and feel across different devices.