I've had a few Boker folders in my stable that were ceramic. They held a great edge for what seemed like a long time, but were on the brittle side. Both had to be sent back to the factory to be touched up. Certainly ceramics have their obvious plus side. I know that NASA could chime in here at this vantage point.
I do have a Mission MPK which has been all over the place. Some people have hefted the knife and can't believe the light weight, others think that the rockwell is too low to maintain an adequate edge. I have used the knife for years with nary a problem. The blade is very tough and keeps a good enough edge for my purposes. It also goes on my numerous fishing trips and I never blink an eye when the salty brine engulfs my cutting implement.
Steel. Yes, got to have it. It is just part of the serious addiction. Steel is not going to vanish or be replaced by either ceramics or titanium. Each material has well known positive attributes as well as negative ones.