I found my old Game Boy advance SP the other day, buried in the depths of my closet. I turned it on and Fire Emblem was inside, can you believe that whole era is almost a decade old now? Anyway I was flipping through some of the character support conversations and one of them revealed the ages of two characters.
One was fifteen, the other fourteen, and here they are in a battle against bloodthirsty psychopaths to save the world, surrounded by other people their age and a handful of adults who sit on the sidelines while children lead them. Not to mention, those two characters had the most...enlightening conversation. Basically went 'Hi! I'm so and so and I think we should be friends!' 'omg cool we're almost the same age lets hang out!' Right. Top of the line stuff.
Perhaps it never bothered me back when I was that age, but now it just doesn't sit right. And its hardly limited to Fire Emblem. Japanese games in general seem to be filled with children/teenagers saving the world for some reason or another. Granted their are exceptions, but I cant think of anything to prominent. Maybe that 'Nier' thing?
But then I look at something like Dragon Age, or Fallout (perhaps not the best examples but eh) where its fairly clear all your characters are fully grown adults whose balls have dropped, voices have changed, and could realistically be expected to actually know how to fight, its kind of...strange.
I'm not interested in arguing which one is better (if anything Dragon Age II shows Western RPGs are heading down the path of barely being RPGs, as Bioware claimed of JRPGs). I'm just curious, what causes this? Because lets be honest, the 'children saving the world' trope is all over the place in anime/manga too, and is for the most part completely ridiculous. The argument about Western beefcakes and Asian prettyboys might blend with this, but I don't really care about that.
Pics also bring up interesting points, though the second isn't exactly limited to Japanese games.

Ellen Baker’s Illustrator: “Keep It Clean!”
Bullet Girls 2 Goes At It From All Angles
Sword Art Online: Hollow Realization A Real Grind
Kashiwazaki Sena Cosplay Pure & Innocent
Koutetsujou no Kabaneri Immensely Gruesome