Now we’ll never get the canon story of how Luke ended up after ROTJ.
Its like Bond just getting his license to kill and then we never get to see anymore movies.
That’s just patently false. We’ve had two different continuities exploring what happens after, and just because it wasn’t written by the original author doesn’t mean it’s not canon. Besides, Lucas never even wrote TESB or RotJ.
Lucas wrote all six movies he was involved in.
Leigh Brackett, Lawrence Kasdan, and Michael Arndt would probably disagree with you.