Them being child soldiers since birth was more based in a throwaway line in The Force Awakens to justify not using Clones. It’s reintroduction in Rise of Skywalker is just to help justify sidelining Rose after the backlash by creating Jannah. It was never about storytelling or world building, unless you want to read Trevorrow’s script; it was about throwing shade at the prequels initially, then giving into toxic fans on Reddit.

I think that having recruits who want to fight are the real alternative to droids/clones/child soldiers because they are actively choosing it. That makes more narrative sense in the context of what’s going on. People who actively choose to be soldiers are generally far more loyal than people who are forced… if only that were a plot point on screen.