It misses having a custom scheduler option, like Java and .NET runtimes offer, unfortunely that is too many knobs for the usual Go approach to language design.
Having a interface for how it is supposed to behave, a runtime.SetScheduler() or something, but it won't happen.
I find it hard to believe the people who built Go, coming from designing Plan 9 and Inferno, would build a language where it is difficult to swap out a component.
I have this feeling that in their quest to make Go simple, they added complexity in other areas. Then again, this was built at Google, not Bell Labs so the culture of building absurdly complex things likely influenced this.