I guess I shouldn't have said they don't develop, implying that none of them do at all. I mean generally, there isn't a lot of overall character development. I think this is in part because Sephiroth is so highly developed, some of that time or focus is taken from the playable characters.

Let's rate each of the playable characters' development, on a 1-10 scale:

** OPINION ALERT ** OPINION ALERT **
************WARNING************
O P I N I O N INC

Cloud: 5

Barret: 4

Vincent: 2

Nanaki: 3

Tifa: 2

Aeris: 4

Yuffie: 2

Cait Sith: 4

Cid: 3

Sephiroth 7

That's an average of 3.5

Keep in mind, this isn't just about where or not the character develops, but whether it develops well--whether or not the character development is only a plot device (Cloud, Aeris, Cait Sith anyone???) or a gimmick or nonsensical, etc.

Cloud doesn't make the story. The story makes Cloud. In this case rather literally. We learn more about what Cloud is not than what he really is. That's not good character-driven storytelling.

As far as Barret goes, his development is almost entirely tied up in his motivation for fighting against Shinra, and for the planet. He's an eco-terrorist because he cares about the planet, no it's just a revenge thing b/c of Dyne, no he wants to save the planet for Marlene. That's it. That's his development.

That doesn't mean you shouldn't like the character(s). It doesn't mean I don't like the character(s). It just means it's not quality development. Sorry.

I'm not a FFVII hater. I've always loved the game and most things about it. But it doesn't have stellar character development. Perhaps it has relatively good development for a Final Fantasy, but that is (sadly) not saying much. However much I love the series, however much I may like the characters, they're not deep, they rarely make sense, and they are, more often than not, simply plot devices.