…and yet we still do not have the streamlined authoring experience we had with Flash. The stuff you show is just a crappier way to write boring GUIs with some other language for which you need to download the runtime. Flash let many more people create far more fun stuff than any Web standard ever did.

People forget that Flash also brought C/C++ to the web at some point, but besides some flashy demos, nobody really cared.

The problem is that all this choice creates fragmentation, you have dozens of platforms within a platform on top of another platform. Web APIs and Javascript may suck in many ways, but at least the are a common denominator.