Why is Mr. Freeze never used anymore?

Is it because of Arnie's debacle with Batman & Robin? If so, that was a long time ago. The character has so much potential, used probably most recently and popularly in the Batman: Arkham games to perfection. His stint in Arkham City was especially great.

It sounds like Reeves is going for a dark tone, but less realistic than The Dark Knight trilogy. I hope he shows up somewhere down the line in a movie.