EVERY genre evolves at a snail's pace because fundamentals don't change that much. Usually it takes some big sea change in the medium like jumping to 3D to really shake things up. It took until Resident Evil 4 for third-person-shooters to really find their mechanics and there hasn't been a big moment since. Until then it's mostly about craftmanship, whether in gameplay or storytelling.The problem is JRPGs evolve at a snail's pace. I played FFVI on SNES and didn't care for it and then tried FFX on PS2 to find out in 2 generations the gameplay hasn't changed and got worse in a few places. Does any JRPG even have any kind of systemic elements yet? Like say a fire spell doing more than just "fire" damage and actually affecting the battlefield. Now a lot of JRPGs are obsessed with trying to mix and match action/real-time elements with turn-based elements and it just doesn't work.
And that's mostly where RPGs are at their strengths, using the games to explore concepts and topics. If you're seriously going to claim that stuff like Xenogears, Final Fantasy Tactics, Parasite Eve, Chrono Trigger, Vagrant Story, Threads of Fate, Front Mission, and Saga Frontier are in no way different then FFVI (whether in gameplay or narrative) then that says more about you than the genre. And that's before getting outside of Square with stuff like Tales of, Shin Megami Tensei, Etrian Odyssey, Earthbound, Xenoblade, Persona, Dark Souls, etc. Even when games were mechanically similar they tended to try and say something different through narrative whetheri t was FFVII talking about hyper capitalism and our relationship to our planet, Final Fantasy Tactics using a fantasy version of the War of the Roses to talk about how gaining power means nothing if you manipulate others to get it as you will ultimately end up alone, Xenogears using Gnostic metaphor to talk about existentialism and relationship to god, or Vagrant Story meditating on the subjectivity of memory and the lamentation of the old world. Using such broad strokes with them is nothing more than intellectual dishonesty