Yeah, I'm kinda with you man. Again, I LOVED MBJ's swagger and menace in the role but I never once felt bad for him. He was just a heartless bastard that needed to be put down before going too far. They tried to add some sympathy for him with the whole father angle, but that wasnt enough for me to side with him.
He says at one point "they killed everything ive ever loved!" but that line felt disengenuous because of what the film chose to show us about him and his character. Perhaps if the movie tacked on two extra minutes at the very beginning of him as a child bonding with his Pops and THEN T'Chakka kills him, that already adds a ton of weight and sympathy towards him because we SAW how much his father meant to him. But from what the film shows us, Killmonger doesnt even seem capable of love. I'm willing to bet Coogler did shoot more backstory scenes with him and his father but needed to cut it for pacing/time.