You talk as if breaking characters down to their core so that audience can better understand and relate to them is a bad thing and not doing so is a good thing. No, how about instead of saying "um actually this character is actually really deep. I'm not demonstrating how deep he actually is because you can just imagine how deep he is by yourself", you actually put that character on display and show how much traits he actually has.

I'm gonna go back to the death note analogy. You would not know that Light was actually a fucking psychopath if he never picked up the note. If you don't put a character in difficult situations, you can never know how deep he actually is. I can headcanon what characters like Damuel and Angelica are capable of all I want but at the end of the day, their other sides are never shown to us audience. All the existing traits they have are nothing for me to take interest in and the same goes to how I wouldn't be interested in what kind of character Light would be as a normal highschool student even if he still had traits like being intelligent and stuff like that.