People mainly want Flash to die because it's a closed standard/platform that can't be improved by third parties and has lagged behind modern web standards as a result. Opening up Flash would address that problem and make the idea of Flash on a modern website significantly less horrid.
Whatever flash is, it’s the opposite of “lagged behind modern web standards”. If anything that was the one thing it didn’t do in its lifespan since it enabled apps that are only now html5 achieving parity.
It enabled a consistent cross platform interpreter for javascript and xml based apps.
Flash's selling point was compatibility, which is why people put up with the clunky APIs, performance, etc. If you changed very much of that you end up with something which isn't Flash and is on a steep mismatch in resources versus the huge investment going into web technologies. I don't think there are enough places with massive Flash codebases to support anything like the work going on in the web space.
