I disagree. Jedi can be interesting. In the OT, Yoda was no less interesting than the Emperor. And Luke was also interesting, IMO as interesting as Vader. I'd even say Obi-Wan was interesting.
On the other Hand, Sauron isn't really that interesting and doesn't get that much characterization. Maul isn't an interesting Character either (in the movies).
Jedi can be done in an interesting way. (Of course, if you make the "goody two shoes" their only character trait, they aren't interesting. And evil Mary Sues like the Bounty Hunter aren't more interesting than good Mary Sues like the Jedi Knight.)
Pls add Qui Gon.
Well the thing is, a bunch of Jedi cannot create good conflict unless someone fall to the Dark Side, that's why post RotJ has to add so many imperial/dark jedi/sith/alien invasion/Abeloth whatever, but a bunch of Sith could make amazing plot.