The ability to make space suits and water bags! Maybe with a smaller 3d printer that is used in pressurized areas (like refilling water bags) and makes 'personal' items like suits/tools/meds/etc.
How about some Rad meds (KI Pills?)?! Radiation seems to be the later game's killer. I know that staying in a protected area can allow the rad levels to go down over time but having a way to slow the Rad gain (especially in the early game when you need to stay outside for longer periods of time) would be super.
I love the wall sockets already, but could they be 'reversable'? That way you can have either the 'in' flow side or the 'out' flow side facing outdoors. As for outside electricity, how about a placeable pole (like the nav beacon/light stand) with a number of sockets (something like 6 in and 2 out) on it? It would be a good solution to wiring up outside locations instead of building little half walls everywhere. If it is one of the light pole like objects, it is easy to move and place and will not cast a big shadow on any close by panels. Also, BATTERIES!!! and a way to recharge vehicles (I figure that these things are lkely in the pipe-line).
Would wind turbines make power gen too easy? If not, they would be a good alternative way to make some power.
Speaking of vehicles, modifiable hard-points! Use your con tool to pull the basket off the rear of the buggy and replace it with a crate rack, solar panel, etc.
Finally; half size and double size resource containers.
Another one pointed out by a friend: The ability to mark and update the map. Beacons showing up on the map. I think this could be expanded even more with a data/coms network with the ability to send a nav point to another vehicle/have coms with another vehicle/base, etc when in range.