More "personal" items would not go amiss. The game is set up to want pretty large individual rooms (not sure what the exact parameters are, seems to be a bit over 25 squares?), but there aren't really many things to put in there. Plant pots seem nice, but screw with the priorities for your gardeners so you don't really want to put those in colonist rooms (honestly I think they should be changed to not need replanting, otherwise the metal cost seems a bit obscene on top of the priority issues they cause). Give us a chess board, a bookshelf, maybe even a proper rug. Just some simple decorative items to make things look more fleshed out. Relatedly: Make it possible to carry meals in a stack or something. It looks cool to have individual tables spread out, but given only one meal can be carried at a time, it's really inefficient and just penalizes creative colony design.
I think it would be nice to make the haul order function more as a "prioritize hauling" than what it is now. As it is, you kind of have to manually send them out in that direction, and even then they might decide they're not too interested in carrying it and will only pick up one or two items instead of everything. Not sure how easy this adjustment would be to make, though. (At the very least, try to make improving hauling a priority in a soonish build. It's not terrible yet, but I feel like as you need to add more resources and crafting, the problem will just exacerbate itself.)
Make there be
some way of dismantling/repairing things that were built by someone else. After a siege, you pretty much have to send someone out to stand in a field and shoot at a mortar until it blows up, which is silly. And if you take a pre-built stone building over, your colonists refuse to repair the walls, even if it's in your homezone.
Related to walls: Make it possible to replace walls/doors by putting a structure build order over them. It is extremely annoying that you have to dismantle them before you can rebuild them if you decide to change things.
It seems as though story events are somewhat scripted (that is, if you have a raid come up and reload a save a few days prior, the raid still shows up the same day), would it be possible to have a way of predicting that? Less so for raids (that will probably have to wait until the faction system is more well-established), but for weather reports and whatnot, maybe? Could just serve as a new research item that allows the forecast.
This one may be pushing the lines of cheap, but I think it's feasible in a limited way right now: Prisoner labor? It'd probably be difficult to have fully functional, but I think it wouldn't be too hard to set it so that they can fulfill orders within their prison room (cooking/growing being the most obvious applications, mining probably would be a bit more of a pain to have operational).
As a research option: "Packed dirt/sand". Basically the exact same thing as smooth stone, just for outside of the caves. I understand limiting the free flooring early on, but later in the game it's more of an annoyance than anything else. Throwing this thing in would probably let you delay when you inevitably work on vehicles by about four builds, lol.
Would it be hard to add in a slight boost to goodwill when you kill an enemy of a faction? I'm assuming this is planned regardless once factions are more important, but it'd be nice to help repair the damage from requesting allies to fight someone that supposedly you mutually hate.
I have been playing a lot lately and have found it rather annoying that I miss the message that I'm being attacked and am constantly surprised when attackers show up. I suggest automatically setting the game to pause or slow when a red message arrives that way I will actually notice the notification.
ETA:
This. It surprises me that it's 2014 and it's still not standard for games like this to have a "pause on event" toggle option in the settings. It would be greatly appreciated.