I mean, I feel ya. The web was built for rendering PhD research papers, not the complex, rich, responsive apps we have today. Square peg, round hole for sure...but we been hacking away at the hole for sometime to get that peg in there...and today it is feasible to build these things. But you're right that if the web had conceived of being used for rich apps from the beginning we would have been spared a lot of trouble.
I think, at a minimum, they would have needed support for something like HTML5 canvas. Then Flash would have never happened. HTML should probably should have been XML with a component centric model from the beginning. Modules from the start with JS. Scoped CSS...lots of things would have improved the web's position earlier...but you know, hindsight and all that.
