"Knowledge is power."
That's kinda too short to say, I guess. That makes the rhythm of the sentence awkward. Plus, this is like a quote, so the -dir is justified. In any case, it's not grammatically wrong to omit the -tür here, it's just the sentence feels unnatural without it.
"Knowledge is power." Translation: Bilgi güçtür.
Does that mean - "In the land of the blind, the one eyed man is king?"
I don't think so. It is up to all of us as individuals to make informed choices.