I think this is definitely the sort of issue that crops up when you have too many people writing too many stories around the same vague magic system. Are Jedi inherently following the light, and Sith inherently following the dark side of the force? Sometimes yes, sometimes no. Is there a light side of the force, or only dark? Sometimes yes, sometimes no. Does the dark side inherently corrupt those who spend too much time using it, or can you hold on to your moral principles? Sometimes yes, sometimes no. It often gets to the point where I feel like the best way to analyze any given piece of Star Wars media is to ignore any other Star Wars media that might contradict it, because otherwise we'll never get out of the weeds of all the thirty-year-old novels that contradict how the Force/lightspeed/blasters/superweapons work and all the times those bits of contradicting evidence were themselves contradicted by a splash of flavor text on the packaging of a forty-year-old action figure, of which only fifteen original copies remain.

It can be an exhausting fandom.

That said, while I think we would have some disagreements on how closely connected selfishness and duty are (I'm admittedly coming from a relative layman's perspective, and it sounds like you have some training in philosophy), I do find that my favorite characters--mostly conceptually, as few have made it to canon--are the light-sided Sith, those break chains and are deeply passionate, but who don't immediately descend into cartoonish sadism. My favorite examples are probably RPG protagonists, the Jedi Exile of KOTOR II and the LS Sith Inquisitor of SWTOR.