Didn't read the whole topic but I'd like to point out that luke isn't a pure LS Jedi. His corruption shows in the way he dresses going from white in the first movie to black in the last. It's his potential to fall that palpatine is counting on, and that's why he spends sxo much time trying to convert him.
The lightside of the force is purely defensive, offensive powers are the path to the dark side of the force, period.