i think kishi did explain it in this chapter through shins speech.
he talked about evolution and picking superior genes to continue to evolve ex: uchiha mixed with uzumaki. and how inferior useless genes die ex: sakura haruno.
sasuke chose the superior person to breed with and create an uchiha with a massive chakra tank and strong life force, but decided to dump the child on the one person he knew wouldn't object and that he would have to do nothing for in return.
ive gained some serious respect for sasuke and his strategic mind this chapter