This is a generic argument that can be used against any sort of proposed improvement. “If you don’t like the status quo, use something else”. It also comes off as defensive; I’m not sure if that’s what you intended or not.
I don't think WASM is proposed as an improvement over either HTML or JS. It's proposed as an addition that fills out certain shortcomings for particular niches. WASM is not (currently) envisioned as the "new" way to write for the web, but as a handy capability to reach for if you need it.
I don't think anyone is suggesting that WASM is the new way to write for the web, but I think it's certainly an aspiration that WASM will allow more languages to be used for everyday web development in addition to solving other more niche problems.
It has not been my perception that that's an aspiration or a goal of WASM, but there's much I haven't read. Can you point me to where this is stated as one of WASM's goals?