You have it sort of backwards. These practices are only 'horror' by modern standards, it doesn't make sense to disregard history because we live by other values than an ancient civilization.
children were not always so precious. if memory does not fail me, in the 20th century, there were still laws that stated that children were property of their parents who disposed of their lifes as they wish. that means you could kill your child without consequences. child labor : legal. etc...
Sacrificing children was just another way to get rid of excess population and would absolutely improve the lives of whoever was left.
Any children not sacrificed would have to die by disease, war, or starvation at some point anyway, because again, the population cannot grow above the Malthusian limit.
This core concept - that preindustrial people all lived at their Malthusian population limit - is incredibly important in understanding the preindustrial world and it's shocking that it's not more broadly understood and applied.
This difference needs to be taken into account when thinking about various probabilities in the past.
But from a microeconomic point of view, children were more valuable in pre-industrial times. Most people worked in agriculture or the trades and lived in multi-generation households, and children were necessary to help with chores and eventually take over the main occupation and care for the elder parents. There was no retirement fund, just your children. Food and clothing were more expensive and childbirth was risky, so children represented a major investment. That they were sacrificed is a testament to how much value people placed on the ritual, not the lack of value of children. See also how valuable farm animals were sacrificed.
It might have been different between infants and slightly older children. The really young ones died all too often.