The reason FF7 has such a huge fanbase was it being the first 3D RPG along with its amazing ( for its time ) CG graphics and music. The game became a hit and now it shows its true colors. FF7 was not that great. The characters did not act or talk like real people ( the poor japanese to english translation doesnt help either ). The story was lame, all you do is follow Sephiroth around the world until you catch up to him ( yes, some plot twists do make up for this ).
The fact of the matter is that FF7 was a turning point for ALOT of people. When someone hears the word RPG, FF7 comes to mind because it was the first one they played. But just because it was the "first 3D one" or the "first one they played" does not make it king.
I'm not dissing this game, I'm just brining up some questionable points about it ( after all the thread title is " why is FF7 great" )...
For the record, I played FF8 first about two years ago, and then FF7 and then FF9. Playing FF7 after 8 was a real hard transition, the weird character dialogue being the worst one.