Not including GC would have been a mistake. Having to carry a complete garbage collector with every program, especially on platforms like browsers were excellent ones already exist, would have been a waste.

I think it's a "you don't pay for it if you don't use it" thing, so I guess it's fine. It won't affect me compiling my C or Zig code to WASM for instance since those languages have neither garbage collection nor exceptions.

It's kinda nice to have 1st class exception support. C++ exceptions barely work in Emscripten right now. Part of the problem is that you can't branch to arbitrary labels in WASM.

WASM isn't a language, so them adding stuff like this serves to increase performance and standardize rather than forcing compilers to emulate common functionality.

This allows more languages to compile to it. You don't need to use these features if you don't want to.

Besides making it much nicer for GC'd languages to target WASM, an important aspect is that it also allows cross-language GC.

Whereas with a manual GC, if you had a JS object holding a reference to an object on your custom heap, and your heap holds a reference to that JS object (with indirections sprinkled in to taste) but nothing else references it, that'd result in a permanent memory leak, as both heaps would have to consider everything held by the other as GC roots; so you'd still be forced to manually avoid cycles despite only ever using GC'd languages. Wasm GC entirely avoids this problem.