There are only two types of people with the emotional stability and time-tested leadership it takes to head a group and confront the challenges in JRPG stories.
1. The dark brooding quiet type with a mysterious past and a penchant for not responding to direct questions.
You'll know you're playing with this type of a hero when the character you're playing isn't blonde (Though Cloud in FFVII is still blonde. Maybe he bleaches?). Anything he says reminds you of your favorite Good Charlotte song lyric and beautiful women are inexplicably attracted to him despite his lack of humor, sensitivity, positive attitude and usually memories of the past.
2. The spunky optimistic kid who wears his heart on his sleeve and really wants to help. And is usually obnoxiously cocky.
Above: Would you really want to hang out with a guy who enjoys playing the Kithara with his grandpa?
You'll know you're playing this type of hero if he's been raised by a kind-hearted grandpa and begins the game by oversleeping. The weirdness of old people will have rubbed off on him causing the kid to jump at any chance to deliver anything to anyone. His eagerness to please is only matched by the emotional intensity of your actual cringe when Gramps tells you to take a bushel of tomatoes to all 25 villagers. Oh yeah, and all young heroes grow up in small isolated villages. Duh.
Quick fix: It's pretty obvious the world needs a young, enthusiastic, quiet-type willing to wear black and help bake pies for senior citizens.
In a perfect world: All heroes would be of legal drinking age. Unless there is no legal drinking age (it is a fantasy, after all). After that element of game design is taken care of, create characters with some emotional depth beyond the occasional gruff grunting or extreme eagerness to help the elderly.
JRPGs will force you to team up with an animal, a stuffed animal or an anthropomorphic household appliance at some point. Even when things are as dire and bleak as they can possibly be: you're the last hope for the world, overpowering malevolent forces are climbing the blood-drenched steps to the last haven for good and the list of dead heroes is longer than the list of people still willing to fight. Even in those moments, JRPGs still can't resist tossing in a seven-foot-tall talking marshmallow with a cat on its head or something. Getting the "don't dishonor the dead by making their sacrifice be for nothing" speech from an oversized, delicious looking breakfast pastry tends to put a damper on my willingness to buy into the "serious" stuff going on.
Quick fix: Limit party members to things that actually have a soul.
In a perfect world: If I've got to team up with something wacky, why not make it a giant pair of boobs? Characters in the game will be astonished at the giant pair of sentient boobs following my party around, and at appropriate intervals, say "WTF? Those sure are some nice talking boobs you're adventuring with." To which I'll say, "You're damn right" in my best Barry White voice.
Worst offenders: Cait Sith from Final Fantasy VII. First, the game makes it clear that he's just a robot being controlled remotely by an unseen person. When he bites the big one, after volunteering to stay behind in the shrinking temple, FFVII cues up the sad music anyway. So I'm sitting there trying to figure out when the robot got its wish to become a real boy, and before I can finish, Cait Sith 2 has found his way to the remote island and joined the party. Good thing there was a spare lying around.