Flash and AS3 was so much fun to work in. I completely understand why the industry moved away from it but even today we have yet to fully catch up to all the media animation and programmatic features it provided all in one. RIP.
You can have frameworks which fully generate the JS DOM code for you, allowing you to write complete single-page applications without writing a single line of JS.
Yep, that's the framework, I'm using, too. But most frameworks in the Rust ecosystem can do DOM interop, as the heavy lifting for that is provided by the wasm-bindgen library.
Unpopular opinion: I hope it's going to be a flop (apart from the few use cases where it does make sense). The limitation of having just JavaScript ensures level of interoperability which is IMHO one of the big advantages of web as an application platform. If WASM becomes successful, it will fragment the web.