I want a declarative web. I wish there wasn't a VM in my browser. I want a web where my user agent, under my control, dictates how documents are interpreted and displayed.
So much of information security relies on not letting third parties execute arbitrary code on your computer. The price to view "mainstream" websites is increasingly becoming "allow third parties to execute arbitrary code on your computer". I can sandbox that code and perhaps limit the impact to my privacy (though thanks to processor microarchitecture "features" that's increasingly difficult), but I lose virtually all ability to control the presentation experience.
To be blunt: The kind of assholes that delighted in using Javascript to block opening context menus, blocking "Paste" into password fields, etc, have won. That pisses me off. Developers with good intentions who wanted to make something "cool" end up being the architects of the tools that will be used turn the web into cable TV.
Change your `dom.event.clipboardevents.enabled` in about:config to false.
So WASM doesn't take away anything from us, because we haven't had the "nice" you mention for 10 or 15 years. Sites like HN will stay like this, sites like Facebook will get even bigger. It will happen with or without WASM.
But yes, I do see where you're coming from. You want a less bloated Web, and you're worried that WASM is not going to lead to that, which I pretty much agree with. While I'm saying that cat is already out of the bag and WASM at least has the potential to bring performance improvements over JavaScript (which will be promptly negated by the sites getting even more bloated).