I'll write the reasons why it wasn't likely considered a gem, followed by why I think it is.
Enslaved... The gameplay was mediocre, but the art design and story was fantastic. It's a great experience, that lacks good gameplay, but the gameplay was good enough to not get in the way, and sometimes that's fine.
Pandora's Tower... The gameplay was mediocre, same as above.
Lightning Returns... The story was stupid with terrible dialogue. though it was probably the most thematically interesting JRPG last gen aside from Xillia 2, (it was just written extremely poorly) , the graphics were horrid, but the game was bloody awesome, with a lot of interesting mechanics that spanked the hell out of most other JRPG's (except Xenoblade and Xillia 2 last gen for me). It's was really fun theory crafting different viable builds, that played completely different.
Xillia 2. Best JRPG story last gen, with a top knotch battle system, and it doesn't really get treated like that imo. Terribly boring world design, Reusing the world wouldn't be bad if it was interesting, but reusing most of the same boring world is bad. However, it was an RPG with a great story, and great gameplay.
