Child-like characters?

[Nestama]

They wouldn't be child-like then. They would be children.

Lalas are child-like. They appear as young children, but are fully grown adults.

But SE doesn't like the idea of creating playable children and thrusting them into violent situations where several people are actively trying to murderize you. Remember the entire MSQ and think to yourself that you wouldn't be horrified if a child was doing those things. "Hey lets send this kid alone into the bowl of embers to fight a god because he has the echo and we don't."

As well as being drugged (HW) and almost outright killed in the middle of a war because the Crystal Exarch is really bad at timing his phone calls. Then there's the whole Squadron thing (not violent, but more unrealistic). No adult would be happy to have a child being their leader, or outranking them.