Honestly, I don't think anyone was yearning for the combat of KotOR. KotOR combat was utterly forgettable, largely uninteractive, and pretty much seemed to play itself. Character builds seemed like pretty much anything works without particularly trying and, being d20-based, the level-ups often didn't feel impactful either, especially if you were playing a Scoundrel. Once your character became a jedi it got a bit better but even there there is very little build-up from weak powers to stronger ones. You can pretty much cherry pick all the coolest powers you want and obtain them, so you really don't need to bother with build paths. So it's pretty hard to give a fuck about KotOR's combat. The only requirement to do better than KotOR here is that the combat actually feel like combat and not like time-wasting.
The bigger source of complaints would be if their new action-based combat results in the lack of party members. The other source of major complaints will of course be the revamping and butchering of KotOR's characters and story, as well as derailing the story to satisfy the need for players to experience the "cool stuff" the remaster team threw in. The story and characters still have to feel like KotOR, and narrative pacing matters. This is probably the spot where it can get absolutely clobbered in the customer reviews and even a number of the professional ones.
Another source of complaints would be if they butcher the aesthetic. Redoing it to look better is fine, but if the visual design stops feeling like KotOR you'll lose people. Often enough, remasters seem to just remake all the parts of the original without factoring in how the overall design is supposed to fit together to create an overall mood or impression, which will fuck with the aesthetic side of things. And sometimes remasters pretty much do their own thing and overhaul it into something that doesn't feel like the original at all. There is, in fact, a fair bit of artistry and direction required in crafting a remake that still feels like the original. That said, the original KotOR's graphics weren't exactly impressive, so there's room to improvise without too much critique. It's probably more important that the design comes together and moves through the narrative appropriately than that the design perfectly replicates the original.
And last but not least, there's always the good old bugs, crashes, and performance issues. Definitely don't want it feeling like the Cyberpunk 2077 launch. The whole "We'll patch it later!" mentality really isn't going to save you from a botched launch, and unlike Cyberpunk 2077 you can't count on outrageous preorder numbers, many of which stemmed from company reputation, keeping you profitable through a terrible launch.