The big thing isn't so much the performance of WASM by itself, but rather that this performance enables the use of data models which are different from Javascri

The big thing isn't so much the performance of WASM by itself, but rather that this performance enables the use of data models which are different from Javascript. Typescript, Coffeescript and a host of similar options have essentially the same data model. What makes other languages, like Java, Rust or Python actually useful is their way of handling data. Which is why you can't transcribe these languages to Javascript trivially. Still, the ecosystem of javascript is a lot better than the languages which compile to WASM as of right now. I guess that will change...