when you have a child in stardew valley, they should max out at a new child stage: young child! in this stage, they have unique dialogue, go to penny's tutoring sessions with jas and vincent, and you can give them gifts! at this stage, their birthday can be seen on the calendar.
Wouldn't this have to be unique for every single spouse, though? As disinterested in kids as I am—I share a lot of players' frustration that a Cellar is tied to family, plus the implication that you can't really arrive without a "full" family, meaning kids—if the game treats kids interchangeably that would IMO just compound upon all of these ills. For it not to could proliferate complications, e.g. with other NPCs, so dramatically as to paralyze the possibilities for a lot of other scenarios in other aspects of the game even before factoring in labor to create them, seems to me…
Make the kids unique for each spouse? They didn't even do that for the base game. All that would have to be done is make two sets of dialogue for each dateable NPC, one that's tied to being your spouse, and one for if they aren't. I'm saying this as a modder who has done dialogue sets, they're not difficult to make conditional. Just doing the base work of giving the kid another stage would allow for modders to do so much more with them that it's ridiculous.
I thought the base game didn't purely because they were too young to exert their own personalities in a way that impacted gameplay significantly enough to trigger differing play scenarios. *shrug* I'm not opposed to generic kids, but I do think it would be a missed opportunity, albeit one which, fully engaged, would, as I posited, proliferate complexities. Since I'm not concerned with kids myself, that's another reason to let those who are be happy with generic ones. But I did want to at least advocate for custom ones, because their not being so seems contrary to the ethos behind what I would characterize to be the respectful approach to character for every other NPC. I'm honestly rather appalled to see players clamboring for their own interests without careful consideration of the kid's and how to integrate the two, despite—or even especially because of—their being thought of as extensions of the player's character and the player's own playthrough. CA has said that originally spouses were less cheery and more demanding, but dialed it back for players' sakes; I side with the less accommodating impulse in favor of character development and meaningful story, even at players' expense and demands upon gameplay—a position I readily concede may place me squarely in the minority, and to the distaste for which CA himself has already made concessions, so no need to fear my viewpoint souring the game. (I'd perhaps consign my hopes to mods—ironically enough, I suppose—but iOS doesn't support them and likely never will.)
I admit I'd have a definite preference for a default child, that I'd then mod to my tastes, since it'd be difficult to make kids for Custom NPCs and added spouse choices from the base game. If I decide to marry Marlon, the game isn't going to have a Marlon-specialized child available, and I'm worried that, since you can get children with him just by marrying him as a game feature, that it might bug the game out when advancing from the generic kids to the specialized preschooler. And it's unreasonable to expect a modder to have to make two separate NPCs just because they made a new Dateable NPC to add to the game in order to keep the game from becoming bugged. Jeez. The amount of work I'd have to do with my updated Siv's mod alone on top of the stuff I already do... plus the planned work in other projects this'd add... it'd turn me off modding altogether, tbh. It might be selfish of me, but as much as I love the idea of kids that resemble the spouse in base game, I'd much rather have the default kid to play around with.
