Shjade said:
Except killing the bad guy takes out the last of the Sith, which actually unbalances the Force by making it too lopsided on the good side. Doesn't it?
Nope. Anakin kills the last Sith and then dies, leaving Luke the only trained force user with any real training and ability to develop his powers beyond the instinctive probability-tilting that half the galaxy has.
Luke's not white-hat, he's grey. Over the course of the series he rejects the light-side path of absolute discipline and self-denial in the service of religion in favor of seeking vengeance and trying to get a girlfriend (in the EU books, it gets carried one further and the succeeds at getting a girlfriend, and her being actively evil doesn't really bother him), following his emotional impulses to let his desire for a father win out of the welfare of the galaxy, etc. Then he rejects the dark-side path of seeking power as an end in itself by rejecting both his dad's and the emperor's offers of apprenticeship, and actually converts a dark Jedi away from power-seeking in favor of self-sacrifice.
In a world where all sorcerers have to choose Lawful Good or Lawful Evil, Anakin eventually said 'fuck it' and went with chaotic evil, wiping the slate and letting his son go NN where he left off.
Ta-da, balance.
(Sure, Luke sorta PREFERS the light-side in the same way the average neutral person will always pick good over evil when nothing is at stake, but when his friends or family are at risk he'll take vengeance and directed rage every time. Even his aid of the rebellion is more rooted in the fact that his friends are on that side and the cops have harassed him a few times, remember at the beginning of a new hope his life goal was to sign up to be an IMPERIAL pilot, he has no actual moral issue with the empire itself, which seems to maintain peaceful order just fine.)