Seems like just another one of those areas where Lily never matured past her teenage mentality.Okay, two things,
1. Jerry is a disgusting pig.
2. What is this obsession with dark Jedi and other dark shit? I’ve had this question on my mind for a while.
The Sith get the cool red lightsabers and the black robes and they're mega-super-badasses, unlike those wimpy Jedi who try to talk things out instead of just killing the people they don't like.
Plus Lily's general being a childish jackass with a hatred for authority and expectations.
She can't even be bothered to hold herself to her own standards, so naturally she hates the Jedi who demand disciplin, self-control and maturity from their member.
For her it's all about the power fantasy. To imagine herself as the mega-uber-badass who does whatever she wants and don't take no shit from nobody, which she projects onto the Sith.