Square Enix has a formula and has it down pat. That's not to say all Square Enix RPGs are the same — they're not. However, they do share similarities in character design. Here's why.
Yusuke Naora, who worked on The Last Remnant, explains, "The format of the RPG lends itself well to having a teenage protagonist. Usually you're playing for many hours, taking a character on a journey from a relatively weak state to one of power and maturity, a gameplay journey that mirrors that of a teenager moving into adulthood."
That's not the only reason to have a young protagonist Naora says, but definitely one of the reasons. Don't think Square Enix is doubt free about populating its titles with youngsters!
"We sometimes wonder what we're doing dealing with such young protagonists in our games, characters who don't necessarily speak to us as adults. There's no pressure internally on how you have to make a character. But you do find that there's an expectation of how a protagonist must look for Japanese gamers."
Teenage Lead Characters Work Well in RPGs, Says Square Enix [Softpedia via Dtoid]