The song is the one and only change in ROTJ that I would be okay with, though Yub Nub doesn’t bother me either. I feel like the somber Force theme when Luke cremates Vader is the “real” ending music, and Yub Nub is a sort of diegetic song that Luke and the others are hearing around them with the ewoks while you’re getting ready for the end credits. The special edition celebration music is more appropriate for what they were trying to do with it summing up six movies on a massive galactic scale instead of Luke’s personal story, but neither approach is inherently better.