It’s not, for the same reason you don’t use it against human foes in The Witcher 3; the recovery time is too long, leaving the person doing the dodge vulnerable to follow up strikes. Something that is very easy for an attacker who is pressing their opponent.
It will also prove quickly exhausting. Ironically, one thing Dark Souls does very well is hammer home how tiring combat is. A character who goes in with a frenzied assault will tire themselves out quickly. Similarly, bouncing around like an acrobat will leave them exhausted and vulnerable.
I was going to say something about how stamina regenerates at an unreasonable rate in Dark Souls until I realized I was thinking of Dark Souls II′s stamina regeneration, which scaled with the character’s equip burden (a stat that tracked how heavy their gear was). (Incidentally, Bloodborne uses this same system even though equip burden is a hidden stat. I don’t think Dark Souls uses that, and I can’t remember if it was the case in Dark Souls III.) This isn’t a bad abstraction for the effect heavy gear can have on a fighter. In real combat, a heavily armored fighter will tire out, and potentially overheat, much faster than one in lighter gear.
It’s also worth remembering that with The Witcher 3, there’s actually two different dodges. The dodge roll which sends Geralt leaping out of the way, and a short range dodge with a fast recovery. It won’t get out of the way of a monster’s charge, but can be useful against human foes. These kinds of quick step evasions do have application in the real world. Being able to bounce out of reach of an opponent’s strike, and then come back in is a useful tactic, and usually worth the energy. Unfortunately, it also has some of the same issues as the dodge roll, an opponent who is pressing can continue to do so, forcing the defending combatant to continue falling back, but it can still prove useful in the right circumstances.
It’s probably worth mentioning, with The Witcher 3, CD Projekt Red was basing Geralt’s sword combat on a specific HEMA variant, and recording actual practitioners for the motion capture. It’s not one I’m familiar with, so I don’t know how authentic what you see in game is to the actual style. If, what you’ve seen there appeals to what you want for a character, I would strongly recommend taking a closer look at what the developers were pulling from, and looking around for any making of documentaries they produced.