Go channels are very handy and magnitude of less spaghetti than futures. And goroutines have good performance.

I think people are used to futures etc, that's why the new concept feels strange.

I think the goroutines and channels are the biggest features which compensates for generics.

Each code in each goroutine is synchronous. That's what makes it simpler than callbacks.

Callbacks are prolific in Go; not sure where you're getting this from...