Also, there is a saying, if it is not broken, don't fix it.
I just saw this review come up on GOG.com's entry for Beyond Divinity, in terms of its prequel, Divine Divinity. The problem, of course, is that Divine Divinity was horribly fucking broken. It chases constantly (literally, on my laptop, something like every 20 minutes. Going through doors made the game crash) and quests could break *very* easily, often as the result of the player either not doing anything, really, or doing something that they had know way of knowing they shouldn't be doing.
The thing was a goddamn mess and needed to be fixed, somehow.
The problem with a lack of evolution in JRPGs is that most JRPGs are horribly fucking broken and need to be fixed. Except nobody's fixing the problems inherent to the genre. There's this pervading sense that, instead of JRPG devs going, "Well, we tried doing XYZ in our game, and X worked really well, Y needed some polish, and Z was just bad, so next time we'll fix up Y and skip Z altogether", it's like, "Well, we tried XYZ in our game. Fuck analyzing how it worked out, next time we're doing ABC."
There's very little *progression* there. There's no learning from mistakes or iterative development or whatever. And when they do go down that rate stuff starts getting kind of tepid since it's mostly just refinement without adding any new ideas.
(And WRPGs have pretty much been set back infinitely by AD&D and Bethesda so whatever).