I'm nearing my first playthrough end, and some suggestions from others that I either agree with or would add:
Building
* [mentioned before] Existing roads should be easier to see during the building process, for both building new ones, but also when placing buildings.
* When placing a building, when you are planning to intersect an existing road, add a confirmation box. "You are placing this building on top of an existing road. Proceed?"
* On buildings that require electricity and water, show the power/water missing icons when you are still putting them down. The radius of such zones is not always clear, so I've often had to add a water tower because it seemed to touch the building, but in the end didn't.
* Don't stack notifications of multiple buildings complete
* [mentioned before] we should be able to build upgraded buildings after they are researched, like the burner; I would argue you need to have upgraded to it at least once to build the upgraded version instantly
* Decorations need to impact the game other than visually
* more variety in entertainment!
Colonists
* it would be a welcome addition to prioritise carrying of certain items, so we can micro better what is being built (say: priority on transistors in end-game is really a welcome feature); I would imagine this as a menu in which we just drag things higher-lower and make this colony wide
* seeing how many children are in school and out of school would be good so you can provide good education for all
Resources / storage
* add the ability to make warehouses reject all resources with one button, so we can just add a few instead of disabling all
* [mentioned before] pantry is a great suggestion
* Don't stack notifications of resources depleted
* [mentioned before] Carcasses should decay over time
* [mentioned before] weapons are too valuable - I also use them to buy anything and everything (all of the time...)
Electricity
* [mentioned before] powerlines! YES!
* [bug] I cannot upgrade my existing lightning rods; I can only build the upgraded versions separately
Technology
* [mentioned before] costs should scale harder; early research is very expensive whereas the later research is ridiculously cheap.
World Map
* [bug] The generated terrain can cause block-offs from zones when there's a building placed in a 1-tile gap, leading zones to be fully inaccessible when they are on the edge of the world map.
* specialist should be able to exit the car into fights/scavenging instead of having to move out and then performing their action
* bandit camps should recover health over time just like specialists
* [mentioned before] giving fuel to specialists to activate cars is a great idea