The Go team does want to innovate on the toolchain. A key factor in the design of Go is the belief that once a language is "good enough", developers are better

The Go team does want to innovate on the toolchain. A key factor in the design of Go is the belief that once a language is "good enough", developers are better served by a superior toolchain (and specifically faster compilation) than by a fancier language. They want to own the toolchain so they can optimize it for Go and make their own tradeoffs about speed versus features.