Let's not pretend people acknowledge warnings, though. It's a popular meme that projects will have hundreds of warnings and that devs will ignore them all.
There's a perfectly valid use case for opinionated languages that don't let you get away with that. It's also similar to how go has gofmt to enforce a consistent formatting.
Honestly, I've been using Go for years and this unused variable error rarely comes up. When it does, it's trivial to resolve. But the error has saved me from bugs more often than it has wasted my time. Most commonly when you declare a new variable in a narrower scope when you intended to assign to the variable of the same name (since Go has separate declare vs assign operators).