(read this as fast as you can to achieve the proper effect)
I think the real reason Jedi didn't wear armor originaly was because the force was far superior to any armor. I mean armor didn't seem to do much good for all those storm troopers Hans solo took out with a single blaster bolt. When Vader deflected those blaster bolts he was using the force not his armor.
In the D20 system there is an insane focus on 'balancing' they restrict force powers for implants which goes against what we knew about vader then rewrite the whole thing to try and make it make some sense. I guess this is supposed to prevent power gaming but thats what Starwars is about, if you're sith! It would have made more sense to tie power gaming to the dark side, or here's an idea, make the force trump just about everything short of a mandalorian basilisk(and even then...).
Vader wore armor, that armor had a life support system built into it. His cybernetics were not part of the armor as far as I know(they may rewrite/mess this up in episode three). I always assumed he didn't use force lightning because he couldn't(Force lightning being a uber-sith power he hadn't mastered), the idea that he couldn't because his armor was blocking his connection to the force or because he'd hurt himself is pretty lame. The force is connected to everything, Bastila uses the force on entire armies with two ship hulls and hundreds of miles of space inbetween them, but slap on a cod peice and suddenly my connection to the force that binds all life together and guides the universe is dimminished? Nonsense.