Also, I don't see a upside of randomly killing child NPCs. Unkillable kids outside of story beats perfectly consistent with CDPRs prior games, and I never felt like "man Geralt should really be able to kill the kids running around the streets." Would randomly killing kids make a game more immersive? I think not. Do I think there may be times kids may die as a result of actions taken in the game? Yes (like the kids potentially killed by the Crones in TW3). Do I think we'll be killing kids ourselves? No.
Minus we don't play Geralt, we're
supposed to play someone we create and be able to decide what that character is thinking.
Maybe we'll go for the roleplay of a Cyberpsychosis V who consider meatbags as cockroach he needs to cruch, or simply a serial killer who likes to prey on kids.
The fact that you don't like to play such character doesn't mean no one does.
Aside of that there may be times when those kids may just be collateral damages, but if they are the only NPC who survive unarmed it do breaks immersion.