You can get text out of WebAssembly as well as you can get text out of minified JS.
Further, users don't care about this. It's literally just developers. Open Source / Free Software is a super valid discussion to have, but I highly doubt any non-technical user cares.
Amusingly, pcwalton brought up this discussion recently: https://twitter.com/pcwalton/status/872151997473972224
But I looked it up and it seems WebAssembly preserves the structure of the original document, just like minification, at least that's what I understand from the following quote:
"In practice, outer blocks can be used to place labels for any given branching pattern, except that the nesting restriction makes it impossible to branch into the middle of a loop from outside the loop. This limitation ensures by construction that all control flow graphs are well-structured as in high-level languages like Java, JavaScript and Go." See: https://github.com/WebAssembly/design/blob/master/TextFormat...
I am delighted :)
Also, it probably means the end of the Web as we know it.
Browsers very likely should treat closed source like they treat our microphone or camera: don't give access unless the user consents.
But do allow it to run without consent if, and only if, the source code is public.