The reason sectors aren't a hot topic issue anymore is that they essentially capitulated and allow free redevelopment of sectors, which is pretty much what I think literally any reasonable person wanted, because of how nonsensical it was that you were saddled with a sector AI you couldn't technically turn off, but which also could be entirely sidestepped with some micromanagement, turning a QOL micromanagement reduction tool that you would find in other games into this invasive thing that created MORE mandatory micromanagement because the sector AI was so bad that even if you were content to let "Governor AI" work in other strategy games for you Stellaris sector AI just... destroyed your empire if you didn't preempt it.
Sectors existing as an efficiency penalty for larger empires, and of course laying groundwork later for internal politics, makes perfect sense, the ONLY thing about sectors that really ticked people off was mandatory AI that existed for essentially no reason, and now that is, essentially, gone.
Now that mandatory AI is gone the main thing about sectors that could use work is just UI redesign, like allowing you to click the sector to see the planets in it while looking at the map, and maybe giving your core sector its own representation on the map just so that you can have a uniform "In character" sector map. Perhaps also the ability to see other empire's sectors. But nothing about sectors is really game critical anymore.
Of course sectors are always going to feel a bit lack luster until internal politics becomes a bigger thing and we start seeing things like sector specific factions that aren't just separatist factions, sector relations, tourism, sector homes for leaders, sector based political voting/power blocks depending on if your a democracy or empire, ect.