Yes, “somehow Palpatine returned” was a terrible plot line. The rest of the Star Wars canon is adding things to try and fix it.

If a character just reappears with no context or consequences, that’s terrible.

That just isn’t what’s been happening. People make up stories saying “Oh it could happen” without looking at the reality of the actual media where it didn’t happen and isn’t happening. If a character returns it matters. It has context. It has consequences.