There's not a lot of good reasons to use WebAssembly for most apps. You need code that is performance critical with light IO/DOM access, and can be written in the handful of languages that can be practically compiled to WASM, i.e. not just porting the runtime to WASM. Fact of the matter is that JS has evolved to be the best language for most front end development tasks. It's scriptable, somewhat performant due to JITs, quite good for single threaded async reactive programming and actually can be written in a nice pseudo-functional manner. And the libraries are quite good, even if NPM gets some hate.
