JRPGs have about as much evolution as any genre currently our there in all honesty. You'll be pushed to find an JRPG released in the past few which still uses the old style turn-based combat and random battles outside an handheld console. The only exceptions I can think of are Persona 4 and Lost Odyssey. Shooters are still generally the same as they were 10 years ago, cover was added and a few other minor things. Sports games have hardly changed either. Even WRPG's if I'm honest, outside Mass Effect, which one can argue is an WRPG TPS hybrid (Which admittedly is an interesting experiment but it is more mixing genres rather than adding something entirely new), have only evolved as much as JRPGs have in the past 10 years too. After all Baldur's gate had choice too and the gameplay is fairly similar, other than the technical improvements over the years, which can be said for every genre.
My point? Pretty much most genres are in stagnation at the moment. The difference between Mario, Starcraft, WRPGs and JRPGs? The former 3 appeal to the western audience more, so they complain less about the genre being in stagnation because they don't mind it as they enjoy the general formula to begin with. I guess it boils down to since games cost much more to produce now, it's harder to devote so much money into something other than a formula they know will sell well. At least that was my take on the situation.
Now as for the original subject. I enjoy WRPGs and JRPGs for their own reasons. I'd hate to see all JRPGs becoming WRPG's, it's boring if all games follow the same suit. Although I can see it happening considering the japanese developers are wanting to appeal more to the western audience. JRPGs need to expand in their own way. Problem is, people moan if they do try and change things, like what happened with both FF12 and FF13. Which does bring up another point. How can JRPGs change that much if half the fans of them don't want them to change? Same can be said for every genre. You can't please everyone unfortunately.