I’m going to go out on a limb here and say making the SEs was his worse decision, not just burying the originals.
It was the beginning of the slippery slope that brought us both the current state of the SEs, the absence of the original cuts from the public domain, and the dismal quality of the prequel movies.
If he hadn’t decided that the OT films were incomplete pictures, he would have had to make prequels that were compatible with the existing narrative and style. Instead, not only did he modify the aesthetic of the originals to match his vision for what became the prequels, having already opened the Pandora’s box, he went ahead and made further changes as he was completing the PT instead of ensuring continuity in style and story telling through PT production alone.
In away, his decision to make the SEs damaged both parts of his saga.
That’s one way to look at it, but I still don’t think think there’s anything wrong with him wanting to make an SE. In fact the 2006 Limited Edition DVDs would have been perfect if the theatrical disc had been looked after to the same extent as the SE disc. Cut the film in half and have Jar Jar Binks singing at the camera for 60 minutes and it wouldn’t matter so long as the originals were available.
You can argue him going nuts with the SE caused the burying of the OOT, but that began well before the SE and he’d already done it with several of his films prior; SE or not he was never happy with the original films.