Having tools that can spot errors early, help you track them down quickly and help you comprehend, organize and refactor your code can be very useful with a large codebase, and I don't think it's fair to characterize that as "you need an IDE that speaks the language in order to write anything efficiently."
Yes, Gosublime is a good example of how tooling can be helpful, though from what I can tell it is somewhat less helpful than what you'd expect in a decent IDE (e.g. no refactoring support, the interface is mainly dropdowns, weak support for finding definitions and usages).
Really, all I need is gofmt on save, and even that is mostly because I've gotten so used to it that I drop ugly unformatted dreck into my editor and let gofmt clean it up.
I worked full time for year without go to definition, mostly because full text search is almost as good most of the time, due to how regular formatted go code is. I don't really use anything else, mostly because I don't need anything else and I have better things to do than install editor plugins.
Yes, but it had the One True Format, which is the only way it can possibly work. I've used a formatter at other jobs in other languages, and you end up having your formatter fighting with everyone else's, unless they're configured exactly the same, which no one can ever agree on.
