That's really the main benefit of sectors as it stands, with automatic upgrading of buildings being a minor secondary benefit. Having a second, third or fourth stockpile of minerals is enormously valuable during the crisis or large war, no doubt, which I discovered to my detriment in my last game where I had only a core sector. It took many years to rebuild between each sterilization hub assault.
The main reason I avoid sectors right now is because of the poor AI choices. If I tell the AI to respect tile bonuses then it produces all the food ever and builds nothing but engineering facilities on science tiles, but if I tell it to do whatever it wants then it builds things in stupid places. And either way, if I tell it to build robots, it puts them in the worst places. Droids on monuments while the weak organics work the mines? Must be a great idea. And either way, it'll build things I really wish it wouldn't, like clone vats.
You can override its decisions, but it's a pain, and you can't even build up the initial set of all buildings on a new colony because you have to upgrade a ship shelter after 5 pops before you can build things like mineral processing plants or paradise domes.
..although, now that I think about it, you can create sectors without planets, right? So you could set up sectors over worthless systems and just send the sector minerals or energy credits whenever you're getting close to your cap. Arguably more useful than resource silos.