I guess you aren't aware that Google Go has their own compilers based on Plan 9 C compiler called "6g" or "8g" (depends on what architecture). These compilers produce much less efficient code than gcc does.

Yes, gcc now also compiles the language, but they still pimp their own compilers... iirc the "go" tool uses them by default (or maybe exclusively). Why create a new compiler? Why a project management tool that does everything except work with other build systems? Why isolate the language by making it difficult to use with others? I feel those are good questions to ask.