1 problem with Oblivions combat was that doing quests or even exploring the land endend in battle.
For an example:
The Mages guild could have revolve around actually study in magic. They could have made puzzles to solve with your magic powers. Maybe you need to move stones that block entrences with telekinessis, or you need to learn how to tame your summoned daedra. But no, instead a released prisoner with 9 recommendations is assumed of knowing how to peform magic, and are casted into dungeon dwelling.
The same with town quests. There was no quests where you are asked to throw drunk people out the tavern, or a task where you was to study the doomstones wich could have had an interesing lore.
1 last thing that gave a - to rollplaying was that every quest many thins was linaer. To get through a cave, you have to fight against monsters. Thats good for warriors, but for thieves they could have made the player able to trick bandits to think you are a member or even perssuade them if youre speechcraft is good enough.
I really hope that the next TES actually lets us play in different ways with different characters.
That's not a "problem" with Oblivion's combat, that is a "problem" with the entire Elder Scrolls series, one that is not likely to be "fixed" soon.