I think you missed the point, and it's a good one:
There are still pretty decent sized issues in the game and "sectors still don't work" has become background noise for Stellaris because, well, every time the devs "fix" sectors it only becomes broken in a different direction. Yes, right now it is "broken because it doesn't work at all" and we're all micromanaging our empires, but there is an entire mega-thread where a LARGE number of forum-goers said that is pretty much exactly what we wanted. IE: "If you can't make sector AI perfect, just remove it and make sectors just lines on a map with governor bonuses and let us manage it ourselves!" Well, that's what we got in 2.2 (even if it was unintentional) and people are now howling for it to go back to the old system.
The irony of it is mind-blowing.
So, I know I'm one of the resident people that likes to make long-winded posts that point out every. single. thing. that the Stellaris team does wrong and how they've failed spectacularly on 2.2, but as far as sectors go I'm going to do something you won't expect:
I'm going to side with the Stellaris team.
This should be priority 997 out of 900. It shouldn't even make the list of things they're worried about for this DLC's corrective action. Not even 1 single hour of developer time should be wasted on correcting sector AI. Not one single minute, even. Get the rest of the bugs worked out, get the AI managing its economy and fleets, make it so a hands-off game can resist an end-game crisis, do All of The Things in the bug forum. Ignore sectors completely.
Because the diplomacy pack for 2.4, which should include internal diplomacy and factions, will include a massive recode of sectors. And that will be sexy.