Apparently there were some design issues (raised and ignored) that made it unusable for many languages.

Ignored is a little unfair to the Wasm committee, the Wasm GC is constrained by what is possible to ship in existing Wasm runtimes and the stuff needed by many languages is way beyond what those existing runtimes have available to them.

I think it made sense for them to compromise, at least on the initial version of Wasm GC, to get it out the door. I say this as someone who wants the features that got left out, like interior references :)