I actually had a decently working ARPG engine going for CC, with dialogue boxes, combat, stat growth, inventory, map warping, allies, save system, and a couple other neat features. Unfortunately, all these systems had to be tied together and so there was a lot of planning involved and integration (and headaches). I also had several revisions in an attempt to streamline everything and minimize the amount of events used.
But the engine is only the foundation, and houses are built with far more than just the concrete beneath them. Possibly an RPG's most important piece is its story, and stories themselves take a lot of work to develop as well. Then you've gotta conceptualize and create all the assets that any game would need. Hero and enemy sprites, environment sprites, various sound effects, music, fonts... goes on and on.
That said, I'm sure there are a few people here with an RPG in development. C2 is still really young though, and large ambitious games take a long time to create, so not seeing any of those is to be expected at this point in time.