I think it depends heavily on how it's presented, but overall I think it's not something that a game developer should bet all their money on. Morality is heavily ingrained in people, especially those who make an active attempt at showing it. Personally, I don't believe in morals, because most "moral values" I know about are vague and "true just because they say so". I prefer the causality of human ethics. And the idea that kids are discarded isn't just another moral flavor, it's a core human ethic and highly unscientific and irrational. All people are good for something. They don't need to be good for more than a select few things in order to deserve life, because we almost always put out more than we get in. Especially when looking at human beings as groups and societies, and going beyond the isolated individual.
If anyone would find this enjoyable, it would either be because of a highly exceptional, rare set of "moral" values or in spite of their otherwise common morals (because it's a computar game fantasy and not real life).
You also have the macro-evolutionary problem. If parents can just euthanize their kids everytime they throw a tantrum, then a number questions arise:
1. When did this change of morals occur?
2. How come society hasn't become extinct yet?
3. Would there be additional rules to this moral that tells you to only dispose your kid if society has enough kids to survive?
4. Would kids' tantrum be clearly known by the kids themselves as punishable by death?
5. Do parents only dispose kids within a certain age range? (as to prevent younger kids to be disposed for don't understand the consequence of tantrums)
6. How many kids do people have, and are pregnancies common enough to physically support this moral?
(and so forth)