You can use the _ signifier to mark imports as optional during development: use
import _ "net"
Make sure you don't check such lines of code in to your repo, because there is a concrete benefit to having the language enforce this import strictness.
But the person who would check in code with unused _ imports, would probably abuse a hypothetical "allow unused imports" flag in production. Go is probably not for that person.
Most Go developers just use goimports. So really this "unused import" warning is a "you forgot to push the magic fix-it button." (Why didn't it push it for me?)
Or more to the point, if Go can figure out imports, why require them to be explicit at all?
But the person who would check in code with unused _ imports, would probably abuse a hypothetical "allow unused imports" flag in production. Go is probably not for that person.