The problem with video games and binary sizes is that the assets (3d models, audio, etc) take far more space than the binaries. And its much harder to compress then while still getting good loading times and high quality.
That's a bit of a separate problem since assets can be downloaded as needed in the background while the game is already running, but to even start the game, the first thing that's required is the WASM asset blob so that should be small.
Ah that is true, I forgot that you could stream assets via web in a browser. But, surely if you can stream the large assets quickly enough for a decent experience (even with caching) then the initial blob size isn't going to take too long to download in the first place?