I don't program in Go. But I could imagine that I might at some point want to sort a list of a custom struct by one of its members. And that's probably as advanced as it would get for my purposes.
As for that use-case: Go generics currently don't have a way to constrain on struct fields. So that will always have to be done with some sort of custom comparison function written by the user of your code, which returns the appropriate field.