Ok, I understand that. By "hacker" I didn't mean "the one who can break systems" type, but "the one who can build and tweak systems creatively" type of hackers. SE is purely a black hat skill. Yes, it takes some skill and even creativity to social engineer, but it still is what it is: immoral cheating. That's why I'm confused.
There is the The Art of War angle. "Know thine enemy".
i.e. "White Hats" should be interested in SE simply because it is a "Black Hat" tool.
Social engineering simply means to lie to other people, manipulate them and cheat them to do harm.
I disagree. The main goal of SE is to advantage oneself, not harm others.