It's a big trade-off to be sure. On the one hand, I'm worried about the web becoming more closed-source and less hackable for all the reasons you've mentioned.
But on the other hand, I can't help see the enormous potential of a proper assembly language for web. Web technologies have felt like a massive hack for decades: tools designed for basic text formatting and a bit of interactivity which have been stretched in extreme ways to meet the needs of the modern web. Web applications are the most widely used software on the planet, and if you ask me it's about time developers will have the freedom to develop them in the language which makes the most sense for the task at hand rather than the only one which is available. And I am quite keen to see what kinds of new things will be possible when the ceiling is significantly raised for performance optimization.
Yeah, I feel the same sentiment you described, too. When building a web application, I'd prefer to use more powerful tools than JavaScript, and maybe a sane(r) set of libraries for user interface. There's also value in cross-compiling applications and games to web platform, because of ease of end-user deployment - for instance, games playable without explicit installation (of the game, runtime, and support libraries).
So I have really mixed feelings here. On the one hand, I appreciate the power WASM gives. On the other hand, I don't trust the majority of companies on the web to use that power responsibly.
But on the other hand, I can't help see the enormous potential of a proper assembly language for web. Web technologies have felt like a massive hack for decades: tools designed for basic text formatting and a bit of interactivity which have been stretched in extreme ways to meet the needs of the modern web. Web applications are the most widely used software on the planet, and if you ask me it's about time developers will have the freedom to develop them in the language which makes the most sense for the task at hand rather than the only one which is available. And I am quite keen to see what kinds of new things will be possible when the ceiling is significantly raised for performance optimization.