First of all, Go's parser only parses Go. Yacc parses a lot of things. Other than that :
- you can find yacc files for pretty much anything.
- yacc prides itself on language support. Go shouldn't feel to flattered here, there's brainfuck support too.
- lots of tools are basically yacc + a tiny bit of code, you may want to translate these to go
- Go's parsing sucks (or how you say it : who still writes parsers like this ? Parser combinators are the baseline these days. There's just no way to make a parser easier to change. Who still separates parsing and lexing ?) (this boils down, again, to Go essentially at best being a 1980s programming language)
Go has its own parser already[1], and who still uses yacc? Don't people use Flex/Bison?
[1] http://golang.org/pkg/go/parser/