So the upside of WASM according to you, is that it got greenlit by the standards committee chaired by companies whose business model would've been hurt the most by a competent in-browser sandbox.
For example, the Epic-Apple Fortnite battle couldn't even have happened. Epic would've shipped it on NaCL and users would've been just as happy, and Apple (or Google) would've had no way of enforcing their sandox.
Whew, thankfully we've been saved from that terrible fate of getting to publish and enjoy software without gatekeepers and appstores.
At least I hope you have something to gain from your opinion, as the rest of us certainly lost out.
On the client side, there's just a verifier, and then the runtime basically consists of branching to the first instruction and having at it. Near-native performance and instant startup, you can't do better than that.
PNaCL was proto-WebAssembly and suffering from the same issues. They actually shipped LLVM bytecode, and you had to compile the executable locally with the whole toolchain, leading to quite bad startup performance and a lot of baggage.
Turns out there's no such thing as portable VM assembly. You still have to ship a full compiler (well, JIT) and compile the WASM IR.
Browser vendors have spent uncountable amount of engineering resources on making yet another compiler (actually multiple, since afaik Chrome uses a tiered JIT for WASM), that's neither as good as the big boys, and neither as fast as just running the dang binary.
Ironically, if it was today, Google could have pushed PNaCL without any problem.
Working on that! I'm building hypen.space which is platform agnostic language & SDK for building native crossplatform apps.
It's a WASM engine at it's core, and while currently it doesn't have "package this app as wasm" capability but supports streaming/local apps only, that capability is currently being developed - together with WASI layers for all of the platforms.
That way your app can run either as a browser (DOM) app, browser canvas app, native desktop or native mobile app.
It's still early, but moving fast - I just added accessibility support, and the animation framework will be out this week.
Regarding the WASM disappointed, when I started building this about 6 years ago, WASM was in a terrible (barely usable without wasting a ton of time) state. Now that WASI 0.3 is out and LLMs have sped up development by a large margin, it's in a quite usable state to ship things to production without fear.