Don't know why they dropped them. I think that the polymer market caught up to them in the sense that although you can work on a cz100 trigger and get it to feel pretty good, other polymers came into the market that required no extra work.
Since you say you have multiple czs, I have a question: I handled a cz75 at a gunstore and the ergonomics were incompatible with my hands. The 100 feels great in my hands. I am curious if other cz pistol grips feel like the cz100 in your experience.