Does anybody (maybe it's just me...probably is) realize how cool it would have been to develop the The Knights of Ren into some balanced group? You'd have Jedi's as a polar opposite to Sith's. And Ren's kind of in the middle.
You could have story lines where Jedi's fought Sith's, Sith's fought Ren's, Ren's fought Jedi's. Each faction could have been developed. A Sith falls for a Jedi Princess. A Ren seduces a Sith Lord. Man, that would be endless. Ren's could be the Anti-Hero. Build that up for a decade and a half - and then give me an Endgame.
Disclaimer: That was my 14 year old self speaking. I take no responsibility.......whatsoever.