I've often considered making a Chrono Cross centered game. Trust me; I'd LOVE to do one. The problem I've run into is the fact that in the end, Serge completely forgets his adventure, making it very difficult to make a direct sequel like you could with a Trigger centered game. Another big thing is that Cross has a very different playing style than Trigger, and that is very difficult to replicate or modify in the RPG Maker engine. And last but not least, like Faust said, there is a massive lack of resources.