I would kinda love saving Anakin from turnig to the dark side and letting him raise Luke and Leia in peace. I bet most fans wouldn't like such a thing, though.
I think that would at least be more interesting than just changing Palpatine's fall, but my trust in how Disney would handle the series even without time travel is not high.
I remember people were similarly upset with the prequels as well when George Lucas first made them. So I'm not sure that input from the man that decided to sell the franchise is necessarily going to improve much. If he cared half as much about the direction of the series as the fans do, I don't imagine he would have sold it.
It's not true. He cared, he said so. He considers them his babies, and mentioned that (and was forced to apologize after) that he felt that he sold them off to the white slavers.
He cares as much about it as the fans if not more, and that's why he's coming back to take care of it, because they did such a horrendous job with it. Even despite mentioning what he did about how you deal with an ex: you don't call, you don't check up on her, you don't pass by her house. But because they so disrespected his legacy in an unexpected way, he's coming back.
It was said, but can't be proven due to Lucas' contract with Disney (non-disparaging clause), that he hated TLJ, and Mark Hammil mentioned that they ruined peoples' childhoods. It was a joke, but I Think he meant it, given how uncomfortable he was with the whole thing. He had to tell himself that it was not Luke Skywalker, but someone else, I think he called him Jake Skywalker.
The prequels were disliked by the fans because they didn't reach the level of quality of the originals. It's a small sin. The sequels were hated because they insulted the originals in many ways, it's on a whole other level it's incomparable.