Actually in the firstsecond wave of comics, Luke joins the dark side to locate and raze Palpatine's cloning factory. There's a deeply meaningful scene where Han and Leia retrieve him and have to convince him that he's redeemable after everything he did to fit in.
That was the second wave of comics. The first ones were the ones Marvel put out while the OT was still being made and which continued for a few years after RotJ.
That's the point. It took their victory away from them, and would keep doing so.
The movies fell flat so hard because they didn't use it as a vehicle to explore anything, characterwise or emotionally. They missed the point and turned it into a plot speed bump.