WebAssembly is about an improved Developer Experience. It lets us write in the languages we like :)

I can't say how many times I've reinvented pieces of Common Lisp to do my job. Now I want to start a side project with this.

My only concern with this approach from an ecosystem standpoint is that runtimes (and more importantly, their standard libraries) can be expensive. JS is still the heavyweight engine that everyone running a browser already has installed; a world where the browser has to download a novel runtime per website is going to be hard on the end-user on the back of a low-bandwidth connection.

... but it doesn't have to be that way. Proper tree-shaking of libraries and smart caching of common resources should make it possible for that cost to get minimized or amortized.