I'm an IE veteran too and while i agree that the combat system ain't great, IE was worse in many ways. I'm not defending the way they implemented the combat mechanics but the ideas behind were good and I'm gonna explain why:
Engagement: Has been used in tactical, strategy and even RPGs for a while now, and it's a wonderful mechanic, some classes can evade or shrug the free attacks and classes that are not meant to be trained in melee are penalized for disengaging from a dangerous foe, instead of being able to kill entire groups of melee monsters just by kitting the way we used to do in IE games.
No Prebuffing: It ends up being the same, as a designer you either consider players will prebuff and adjust the toughness of the enemies or you do what Obsidian did and remove a time consuming pointless and repetitive activity. Also, there are still ways to cheat the system and prebuff if you want to.
Limited resources: I don't think i ever used the 4 campfires in my normal run and even in hard i only used them up later in the game because i didn't do a lot of sidequests and was underleveled/underequipied in the last few dungeons. You just need scout so you know what are you gonna use, when you are gonna use it, and how to position your party (Which is essential wen facing incorporeals for example). Tthen again if you just want to steamroll every encounter without taking a sweat you can always turn god mode on which is kinda the same as burning your whole spell list in a single encounter and resting afterward like in IE games.