Lord Janus
Plo Koon Rulez!
No, actually... the conditions surrounding all these characters besides Luke is more feasible.
Take Marka Ragnos. He was of a race that was incredibly Force sensitive, the Sith. He lived for what? A few hundred years? In his environment, Sith had to be very good or ended up very dead. I can see him having some considerable Force mastery, and considering that the Sith empire sat around for centuries thinking of ways to kill everything else, it would nto surprise me that they could do incredible things. It'd be nice if everyone was more even powered, but they aren't. And with the ancient Sith, this is more plausible than some human farmboy who became a jedi in a three week program, beat one lousy assed former jedi in a breathing suit, and then goes on to become the most powerful being in the world in under twenty years, surpassing Yoda! Yoda, who has lived for nine centuries. If anything, Yoda should be the most powerful jedi, period. No one else that i can recall has anywhere near his experience. No, the inconsistancy goes extreme with -Luke- being a forcegod. It's not even remotely explanable by his origins and experience and such, and NJO is a cockup of an attempt to pass off all this ridiculous bullshit.
So no, I don't have a problem with overpowered Sith. Not at all. It's what they do. If the most powerful Sith in the galaxy could only throw rocks and shock people, I would be disappointed.