Watch your PC face in Oblivion as npcs/companions get close use a race/mod with ears as it will reveal when your PC's emotions have changed.
It was the Cliffracers that cured me of 1st. With exception to arrow shots, I like to see my PC in action, especially if it's a half-naked female doing sixy walk in sixy armor... and I prefer to 'see it coming'.
You are right about the 'lifelessness of Skyrim npcs, same with FO series. I think of them as animated department store manikins or script puppets. The animals - motorized taxiderms. Follower/mods are animated nothings. Skyrim is really nothing more than a fancy Morrowind game with more bells'n whistles, but with less mouse/keyboard mobility - a sort of set-action-on-cue, lying 'Harry Skyrim Show'. Hand to Hand is the same and I at least could spin my PC in circles to wack villains at once and attack in midair in Morrowind. I can do a back spin jab in Oblivion.
I use several npc mods in Oblivion, I regularly can across random groups of interacting npcs as if I was in ISO. Oblivion npcs provided their own lively atmosphere. The npcs were always happy with their goofy grins and follower seemed to aquire distinct personalities.
To me, Oblivion was like a dozen steps forward from Morrowind. Then the company seemed change and regressed eleven steps with FO3, then three steps forward with Skyrim. What a let down.