GOPATH is hated because it's poorly thought-out. It's poorly thought-out because Go is designed by Google, who uses Bazel for dependency management. GOPATH is only there because you can't expect everyone to adopt Bazel in order to adopt Go, so some half-assed solution gets designed to get the language out the door.
In simpler terms, the people who designed the language don't use GOPATH at all. That's why it's terrible.
I don't think GOPATH is poorly thought out at all. Dependency-environment-locating is a PITA. Off the top of my head, I can't think of a single package management system that doesn't use universal installs, FOO_PATH or "giant local dump per project".
Rust is probably the least-half-assed (most full-assed?) model, with both a sane user-wide default for cache (~/.local/cargo), a way to edit that default, and project location flexibility.
But I actually love the Go notation that I've opted to organize most of my code around the ~/namespace/src/domain/repo scheme. I never lose track of where a folder is :)
Nope, just two or three. Most lives in ~/ao (easy to type on dvorak), some is in ~/rd (random), some is in ~/tmp. I don't really work on enough variety of projects to deal with collisions.
In simpler terms, the people who designed the language don't use GOPATH at all. That's why it's terrible.