Look at how much demand DF needs though. Even with that I could run it fine on my Toshiba Laptop before I switched to the bulkier TV connected PC I have now. DF still managed to revolutionize (the genre DF literally started btw, so uh, self-revolution) the way colony simulators work with Z-Levels. After that I can't play colony sims with on a /flat/ XY dimensional plane. Rimworld would be much better if it had Z-Levels, especially considering its a Sci-Fi game with guns. Elevation would make firefights more fun, the ability to build high rises, actually being use air travel vehicles on map (maybe when raiders or another faction raid you, they can have gunships), etc.
Too bad Tynan(?) stopped development of the game. Even beside the whole non Z-Level thing, Rimworld just feels unfinished to me. To the point where you need a bazillion mods to feel satisfied. It had potential.
Rimworld development... didn't stop, though..?
In fact, Tynan has been unusually communicative in saying that development
is ongoing. As was noted before in the thread too, the development team for Rimworld is actually growing.
Rimworld definitely doesn't need Z levels by any amount, though. It's very possible that they could improve the game sure, but it's not necessary. Dwarf Fortress benefits (putting aside the nasty tendency to die a horrible death of .1 FPS later on) from Z-Levels due to things like the fact it's about
dwarves who
dig underground as well as the extensive simulation aspects. Dwarf Fortress has dynamic fluids and mechanics based around those. Things as simple as using a well to gather water to flooding the map with magma. Rimworld does not even begin to do this.
Sanctume put it pretty succinctly. DF is more-so a world simulator that happens to have fortress building/adventure mod gameplay attached. Rimworld is solely about that "game" bit, and as a game it's a colony RTS.