The outfits designed so far give you the freedom to choose what to wear while balancing any skills you might lack. Furthermore, more outfits are planned for the future that will feature even more unique abilities or attributes, or even occupy just a single slot. The Frostguard set is an example; it is strong against ice but weak against fire.
While yeah, I do agree that the Frostguard set is very unique, and I get that it needs to take up all your clothing slots in order for the unique battle animation to work, that doesn't help with the "you should have more customizability with your outfits" point I made. The Frostguard armor is good, I agree, and it has very distinct use cases. But, other clothing items let you mix-and-match, letting you make more choices when it comes to strategy and aesthetics. I'm saying that the clothing would feel a lot more customizable if there were more clothing options that were compatible with the outerwear+underwear system, instead of taking up both "slots". Like, if you want to wear the Demonic underwear set, you literally only have 2 options on what to wear on top of it. (or 2.5 if you count the Corsair shorts, but those also invalidate the basic skirt in terms of stats, so it's still 2, really.) It just makes the few items that are compatible with this system feel really useless compared to the two-slot items which are generally better, and sometimes strictly better (the relationship-based clothing items).
I'm really glad that future planned outfits are going to have more unique abilities, though. If all the later outfits just increased or decreased the basic stats, that would be a bit disappointing, especially after how unique the Steampunk and Succubus set are. I personally hope there aren't too many more outfits that take up the whole body without good reason, though.