I think this period is where Lucas feels the main thrust of the story lies, with Kenobi, Yoda, and--most importantly--Vader still alive. I know he had some ideas for a new arc after RotJ, but maybe now he's content to let everyone live happily ever after.
From what I recall of the post-RotJ non-canon books, it gets rather DragonBall-Zesque with A) trading off a sense of wonder for an increasingly dark, heavy tone, B) characters shuffling on and off the mortal coil willy-nilly (that damn Palpatine just won't stay dead), and C) it becomes a total jedi power trip where the dials go up to 11...then 12...then 38...then 5,604....People are using the force to blow up planets and stars.
Having said all that, I certainly think that animation has come far enough that an animated sequel featuring Luke Skywalker, Han Solo, and Leia would be stupid not do do. Now is the time to do it too. In fact, I think such a film would be the breakthrough film that animation has been waiting for: an animated adventure film that can skew to audiences more than six years old.