You know, I watched a Mr. Happy video today about Criterion dungeons and he put out a point that makes a lot of sense:

Mount Rokkon's poor reward structure is the same as the previous V&C because it already 'sailed' (production wise) when the first one was out. He mentioned that the developers explained about a similar situation in Eureka, that only saw major positive changes in Pyros, because Pagos was already ahead at a development stage and they couldn't improve by then.

That's probably a symptom of how formulaic they work... The features across the expansion are consistent in what they deliver, so to change something on the go might not be as simple, sadly... But hey, I'm not a game developer, so that might not even be the case.