Differentiation of the characters in the battle system wouldn't make sense in the world of FFVII.
There is no reason for Barret to not be able to use magic that Yuffie or Cid can.
Making some materia limited to some characters means story changes.
Materia comes from the planet, so there would need to be a reason character x is connected to materia x.
You could make a case for Red and maybe Vincent being able to use specific materia though. And Aeris is the only one that can use Holy.
Besides that, with materia you can make countless 'job classes'.
More than in any other rpg I've played.
In FFVII you create the classes yourself. Hybrid classes, triplebrid classes.
You can even make a Frogger job class. Someone who opens the battle with Toad, counters with Toad, hits with Toad and even uses Toad as a final attack and so.
Its the coolest battle system ever.
''Hadouken!''
