The main weakness in Normal is the lack of Armour (you compare this to the BUNK3R fight, which has a ton of Hyperion robots). The thing is, TVHM (and Mayhem) expands on this by Armouring up enemies (normally Badasses).
The most unique types of enemy in terms of health / shield / armour bars exist in the DLC, true, but I think you’re forgetting Promethea - especially Skywell 27. Plenty of Maliwan balls and mechs in general.
So while there statistically might be less dedicated non-flesh enemy areas compared to BL2 (or TPS), the problem isn’t the lack of diversity. The problem isn’t even power creep. The problem is we have two elements that work well against Armour - Cryo and Corrosive. Cyro in TVHM+ is only 25% less effective than Corrosive. So Armour is inherently less viable as a defensive bulwark. Shield is also heavily countered by Shock (the strongest elemental counter in Normal or TVHM).
There are some issues in that meta weapons often come with multiple elements, but element-stacking has always been “meta” / “broken” ever since BL2 (it’s how Zer0’s kunai build worked, with or without Death Mark). So again, I don’t think it’s power creep necesssarily. Even a crit-damage-build oriented Hellwalker (which is one of the strongest Jakobs guns right now) tickles unless you invest in some elemental modifiers (Zane’s Cold Bore, for example).
Armour was the hardest counter in BL2, basically. There are more ways to counter it in BL3. That’s all.