It was just really well marketed and sold very well, most JRPGs were ignored up to that point by the average person. This was the first FF played by most US (and EU) players.
It was also the first one on the PlayStation which was getting very popular in the US (and I guess Europe too).
Also, most RPGs didn't have 3D graphics at the time, and that was a big change; the FMV and CG was pretty good at the time, all things considered.
Obviously JRPGs have evolved since then, but at the time there was a lot of groundbreaking stuff, and I guess people are nostalgic.
It was also the first one on the PlayStation which was getting very popular in the US (and I guess Europe too).
Also, most RPGs didn't have 3D graphics at the time, and that was a big change; the FMV and CG was pretty good at the time, all things considered.
Obviously JRPGs have evolved since then, but at the time there was a lot of groundbreaking stuff, and I guess people are nostalgic.