The main value of the race detector is enabling it for tests (go test -race), and then writing sufficiently exhaustive unit tests to cover all code paths.
I do think most gophers, instead of tests, use a combination of prayer and automatically restarting crashed processes when they inevitably panic from a race, which seems to work better than you'd expect!
That's "let's run the race detector and get some coffee" overhead, not "let's leave it on in dev" overhead.
Still cool that they have it available!