Disabling auto-promote is good, I like that idea, but I don't get the "new pops promote as normal" part, particularly how it meshes together with disabling auto-promote at the same time. Can you explain further on this?
The main thing that can jar your developing planetary economy is adding specialist jobs en mass. You get hit for the specialist's production inputs plus the resource output lost when your workers promoted.
For example, adding a little alloy production to a mining world can do the following: Alloy foundry comes online, adding 2 specialist jobs. 2 miners immediately take those jobs. Your economy immediately loses a net of ~20-24 mineral production as a result. 12 from the two metallurgists and then 4-6 for each miner, depending on early game bonuses.
By making new pops automatically fill the highest strata jobs, you slowly ramp up the resource demands of the specialist industry you are developing without losing any of the existing worker production. This means you have a smooth change to your economy with only 1 UI interaction, rather than having to enable jobs as you want them.
I think this will only work when you can set the priority of jobs before the actual building providing that job gets built. That will clutter the already small, cluttered UI.
There is a lot of usable space in the job tap, right next to the existing controls. You can convey priority with a number and relative position of the jobs.
As I said above, most problems can be solved by making more intelligent macro level decisions. Introducing more micro so that you don't have to put more thought into your worker/specialist balance and job/pop balance isn't the answer.
Macro level management is the best way to manage this issue now, but requires quite a bit of checking on colonies, which is time the player could be doing something else. If I know what my colony should look like and have the resources to pour into it now, why can't I queue up development and not have to worry about the colony's economy turning into a trainwreck because I added all the spec jobs in this queue rather than coming back and adding 2 more jobs every 5 years.
I think this is too simplistic. I'd want a priority system to be a bit more nuanced, like sliders for each stratum, indicating the relative weight between jobs in the stratum. For example, I may decide I want to keep 2x as many pops in miner and farmer jobs than the number in clerks. So the assignment system attempts to keep the percentage of miners/farmers double the percentage of clerk jobs filled. Pretty similar to wundergoat's idea, just with different UI.
I think that would work great, and actually preserves some of that feeling of pops not being directly controlled by the player. Idea: next to the existing +/-, put the up/down arrows and a number. All jobs start at number 3, and you can increase or decrease that number from 1 to 5, affecting job weight. You can still fully disable jobs with the +/-, but you can also affect job balance.
It doesn't create any micromanagement if you wait until you have unemployed pops before you build a new building.
Checking back on planets is still micro, even if that is cycling through sectors in the outliner to see if there are unemployed pops.
Promotion Policy:
Liberal - Current system. Anyone can promote.
Balanced - Fills the building, but takes workers from whatever monthly resource is highest.
Limited - Only unemployed fill building slots.
I feel like this issue is about how to better control how jobs get allocated, which can be handled now through funky controls and lots of micromanagement. Therefore it is a UI issue and access to better UI should not be influenced by game decisions.