I've always felt as though I'm unable to fully enjoy RPGs. Final Fantasy is one of my favourite series of games, but outside of that it's pretty limited. Undertale was probably the last RPG I played that I liked, mostly because it did something different with the combat system and the puzzle aspects weren't too over the top. I feel the same way about CrossCode, but I would put that game into a different category as it isn't a traditional RPG.
I just don't want to sink a ton of time into a game that is mostly a grind with story elements and payoffs that are few and far between when I could play a different kind of game that is at least continuously stimulating.
Haven't played many RPGs, but of the ones I have, Undertale is my favorite. The others I played were South Park: The Stick of Truth (not a grind, but no unique mechanics, it's really too easy and the comedy is what will keep you playing) and I just started Mother/Earthbound Beginnings (plays entirely like a traditional RPG, the only reason it hasn't struck me as a grind is because it took me long to figure out where to go. Honestly I feel about this one the same way you feel about the RPGs you've played)
I also started Super Mario RPG eons ago on a year 2000 laptop and never got anywhere near finishing it, but it was fun. Don't think I got far enough in it to judge it.