The press turn system does get a lot of praise, but I think fans are mostly drawn to how well the game sells the idea of being on your own in a really oppressive post-apocalyptic world, everything just comes together so incredibly well, the art direction, music, characters, story and merciless difficulty just create this vibe that is really unique, even within the franchise.
I know you're a person of excellent taste
, just my 2 cents.
Back when I had the PS2 I still had a lot of time to play and wasn't very selective which is a huge contrast to where I am right now, so I ended up playing several games that really made me regret the time I put into them. Stuff like Rogue Galaxy, Wild Arms V (I liked IV) and Kingdom Hearts for example.