There are annoying things in TES, for example Cliff Racers, Adoring Fan, Caius Cosades' nipbles and so forth. But nothing beats the annoyance of Greater Bonewalkers. I was in Punabi, doing a quest for the Mage Guild, enjoying the nostalgic feeling of playing Morrowind again, when a Conjurer summons a Greater Bonewalker. I managed to kill the bastards. But then I realized and recalled the horror and terror of the Bonewalkers; my strength was 0. In few hits that abomination had svcked my strength to absolutely nothing.
So I had to drop completely everything, even my clothes, and teleport to Balmora, walk from one alchemist to another to buy restore potions. This is early in the game, so imagine if I had been a warrior or if I hadn't bought the Mark and Recall spells, or Almvisi Intervention. Then I would have to run naked back to town. And it's quite a distance.
Therefore, I say, if Bonewalkers show up again in Skyrim, I'll scream a little, and curse as well, and then do everything in my power to wipe each and last one of them out of Nirn.