GTA San Andreas had RPG elements and sold like crazy. Ditto CoD4. The industry has been this way for a long time.
People like experience points and skill trees. It's the stories, combat, and general eccentricities of the RPG genre that are the tougher sell.
The audience is much smaller now than the 90s, but I do think P4 is sort of the FFVII of it's day. It's one of the biggest niche titles within the niche and it's popular enough that's it's basically a franchise unto itself at this point. We saw Square eventually try to capitalize on FFVII in the same way, but Atlus seems to actually be trying to maintain a certain standard of quality.