You have no idea how hard Asm.js is to "read". Minified JS is okayish. But Asm.js has the ASM name in it for a reason, without proper tools it's even harder to read than any ASM. And WebAssembly is at the moment based on Asm.js in its current alpha state.
That was not my experience when I ported a large C app over to asm/emscripten. The mapping from C was very transparent. I had no problem using the dev inspector to debug the code.
WebAssembly is still work in progress, isn't it? There are proposals to have 2 text formats: low level one (Asm.js like) and more high level representation [1]. So, I'm dead sure the way out will be found. If not, community will create workaround-ish solutions in a form of "WASM -> language of your choice" decompilers.