That's are hotly debated verse. I do think it means don't return evil with evil, but that alone doesn't mean be nice. It sounds to me more like, "don't be an idolater." That is, don't become a false image - your behavior and likes/dislikes can be in the image of god, or something alse ; if else, then that's idolatry.

But there's a deeper layer, which is hard to describe. Nature is unbent, unstraightened, flowing but not conforming or demanding. That's an image of God. We come from that. We do great harm to nature and each other when we impose values onto nature. People sacrifice themselves on various causes by pouring out their lives on various purposes, thinking "this way will be better." But it never is.

I think turning the other cheek is also not harming the world with good intentions. Even if I'm wrong, turning away is not the same as being nice.