"Trivially solved" is a funny way to describe "design 3x as much content" (which is what "including more buildings that do actually interesting things" means in this case).
It's really not. For rural districts, currently in the game are buildings that:
Add +XX% output
Add +X output
Increase the amount of a particular rural district that can be built
Exploit strategic resource deposits (one building per district type)
Automates
Not in the game for Rural districts but absolutely could be:
Add +XX% pop efficiency
A building that adds ~50 jobs
per district
There's seven for you. They're not that interesting individually but that's the low bar I'm talking about for them to be interesting
in combination. If I have N building slots and N+ types of buildings I can build then working out what the best buildings to build in any scenario becomes a puzzle. If I have less than N building types then it's just makework.
"But Critical Ethics, five of those are in the game! So therefore you have what you want!"
Nope. The second one is only available as being applied to an upgrade of the first one, the third is highly situational (and usually strictly worse than just throwing down a +200 building), the fourth is locked behind planetary features, and every single one of them is locked behind a tech. When you first unlock a specialisation your only use for building slots are as near one-for-one trades to help avoid having to build more districts, which is the exact opposite of the entire concept!
If you started the game with three very basic, district-unique buildings (+XX% output, +XX% pop efficiency, and one that does +XX%/2 of both) then building the automation building comes with an inherent tradeoff - you're losing about 20% output (lower due to stacking but you get the idea). The first 15% of the automation is a neutral gain in terms of per-pop efficiency, so you only need to cost off the remainder. Or, better yet, start with two buildings and only two unlocked slots with the third slot being unlocked by any tech from that district's tech tree that also grants a building.
I should also emphasise that I have no objection to buildings that add more jobs, my objection is spammable buildings that do nothing but add a large, fixed number of jobs. So balancing disparate buildings by sticking ~50 jobs onto the weaker ones is not an issue - especially given that they all should still be planet unique.
The automation buildings cost what they cost before buildings were excluded.
As I understand it, the building costs will be back when they have time to fix the bug that made it count all buildings on the planet, instead of only the ones in the district.
That wasn't a bug. I reported it as a bug and they replied saying that they were doing it on purpose but would stop because everyone was
completely insane not getting good feedback. Then they removed the building costs entirely and increased the per-district costs. Maybe they would have liked to include buildings in the rework and couldn't but there would be no need for them to do so if there weren't a +200 jobs building!
I think they're mostly fine. Consider that building a specialization costs as much as 3.3 rural districts: it's more empire size efficient, but without jobs from building slots, it would cost more than it gives you except on fairly large planets.
1) this is only the case if you're looking at the +200 building jobs as the standard rather than the horrible wart on the entire concept that they are. If the standard item you could put into specialisation slots were efficiency and output increasers then even on small planets you'd see returns from the increased pop and land efficiency.
2) if it weren't for the +200 job building they wouldn't need to make rural specialisations cost that much in the first place. This is what I'm trying to get at, they warp the entire game.
That's the core issue, yes. They're filler buildings that mainly exist to fill slots when you don't have anything better to do with them, but their incredible suck field makes it infinitely harder to add better things to do with the slots. It's ouroboros of bad game components.
And for e.g. research... Research labs were fine before, and they're fine now. [snip] and a way to let tall build even taller.
1) They worked fine in the old economy because it was a different economy.
2) A planet unique science building that added additional jobs per district would serve the same purpose without destroying the rest of the game and would work with rather than against the selling points of the new economy.
3) As would districts, buildings, and civics that boost civilian output.
4) Even if we ignore all that and look at if they work less poorly and how we can build on that, any dissimilarities are because they spit out empire level resources. There's no perverse incentives to meet the "minimum science requirement" of a planet by using the lowest possible number of districts like there is with rural districts, so few arguments that work for science labs really apply to base resource districts - and those arguments are best served by options 1 to 3 anyway.
e: The actual big exception is amenities.