TL;DR
There should be higher tiers of concrete with increasingly ridiculous costs for decoration and flexing.What and Why
I think concrete lies at the foundation (pun intended) of every finished base. Is your base really finished if you haven't eradicated all signs of nature and made sure that not a spec of your delicious pollution is absorbed by the land?NO! The factory must grow and said growth must even seep into the ground itself!
Passionate opening statement aside, I think concrete is great.
For one, it is an innate flex to pave your factory as Refined Concrete requires smelting stone, crafting it with water and iron ore and then with more water, steel beams and iron rods. It is hilariously expensive to just a little bit of paving... and that's why it's a flex, a status symbol of your abundant resources and ever-growing want!
Now you could just pave everything with Refined Concrete for maximum flex but I (and some others as I've found) like to use it as our only real means of "decoration" (aside from the inert beauty of a well structured base). So what am I asking for... concretely (last pun, I promise)
When you think about it, the first tiling is stone, the second incorporates iron and the last requires "processed iron". Almost like we're progressing from the stone age through the iron age!
So what should be next then? Plastic Age I guess? With Advanced Concrete requiring the previous Refined Concrete + Crude Oil + Advanced Circuits + Barrels.
Then what? Perhaps the Electronic Age, for Intelligent Concrete which requires Advanced Concrete + Heavy Oil + Processing Units + Electric Engine Units.
And finally, the Space/Nuclear Age, for Supreme Concrete requiring Intelligent Concrete + Lubricant + Uranium Ore + Low Density Structure.
The beautiful thing about these recipes is not just how expensive they are but also how incredibly inconvenient it is.
Are you really going to spend all these resources on some floor tiling? Are you really going to try and fines a belt layout that supplies all these ingredients? What, are you scared? Too poor to afford some floor tiling? Or can you just not do it?
Honestly, I don't even care about any potential walking speed increase because at this point in the game you will long since have unlocked the Exoskeleton and Spidertron so really, this is all about more means of decoration as well as... just flexing on nature I guess?
And obviously I'm also not really hung up about the recipes I listed as they are more to illustrate what I mean in terms of expensive and inconvenient.
There's also the topic of "colored concrete" for which my search yielded this comment from Klonan which basically boiled down to "not now" back in 2020.
When you think about it, (base) Concrete is used in some recipes but Refined Concrete already just exists for player enjoyment, so is asking for more really such a bad thing?