I've explained this many times before. God is the same, both Old and New Testaments. It has been estimated that the number of Hebrew infants the Egyptians killed was at least ten thousand, possibly a lot more. Exodus records how the Amalekites kept attacking the Israelites from behind, meaning attacking women and children, not the soldiers.
Next we take a look at history outside the Bible. There is no indication or word of any tribe or nation known as the Amalekites or who behaved as did the Amalekites. It appears they may have been gangs that preyed on travelers, raped the women, castrated or killed the boys--acts condemned by all tribes and nations, and even by us today. The word is associated with demons and evil. Rabbis have pointed out that it is in this context the Israelites were to completely demolish the Amalekites, down to the last possession, down to the last child. The call was to eliminate evil entirely. This leads to the lesson: Notice how humanity/individuals always keep a little evil handy to play around with. What's wrong with a little adultery, a little divorce, a little abortion, a little theft (shoplifting) that occurs around us. Compare this to someone seeking medical treatment for a cancer growth, all of which can be removed. Who would say, "Oh, just leave a little bit of the cancer...it's not so bad."
So...we have King Saul saying something like this to the Prophet, Samuel: Oh, the leader of this gang isn't so bad--he likes women, he castrates little boys who annoy him by trying to defend their mothers, sisters, and themselves--totally understandable! Besides it's what his his father taught him. And a look at all the fine cattle and sheep he has! Nothing wrong with us being just a little greedy and keeping some of this for ourselves. After all, it isn't going to undo the rape, castrations, and killings this gang did to our women and children. Feed the women and castrated boys a nice lamb chop, and they'll forget all that happened.
What I hear you saying in your complaints about God is that God should relent and allow a little evil in society, that people should learn to be accepting of what some consider wrong-doing, especially when one can benefit from the evil. Raping, castrating, killing women and children should be given a pass. After all, it's only a little evil.