`dep` is actually a good tool and suppose to be the official tool. But out of no reason, `vgo` came out and said to be deprecating `dep`. I don't really understand how the Go team make decisions.
But for all the good this attitude brings (and I would definitely regard it as a net benefit) there have been some pretty huge missteps too, and the Go team's prioritisation of things like type aliases or the half-finished plugin architecture over those missteps leads many to ask reasonable questions about how those priorities are decided.
GOPATH is a long-acknowledged mistake and a lot of community effort and consensus-building work has gone into finding a solution. vgo was a bit of an ambush and has left a lot of people confused and bewildered, especially after a huge amount of community goodwill and momentum was built up around dep. That was a price Russ Cox decided to pay with vgo, which was his prerogative. Now we just need to wait and see whether it was worth it, which will take some time.
If you haven’t yet read it, start here: https://blog.golang.org/versioning-proposal