One bug that I've noticed still occurs is the odd time where your character gets stuck in a spot, and the only movement you can do is spin him/her in a circle as you try and click different spots to move him/her. The only way out is to either teleport or TP, or to save and exit. This happened before D2R as well.
Another suggestion that occurred to me is regarding set items. How many sets are actually used/sought for end game? Tal Rasha's for the Sorc, Mavina's is great for a frost maiden, Trang Oul's for some types of necros, and sometimes IK set for a WW barb, I guess? But are Aldur's, Natalya's, and Griswold's sets ever used in full? And as for the other, non-class specific sets, other than individual pieces such as Guillaume's Face or Laying of Hands, are any of these used at all, much less as a set? The Disciple....Heaven's Brethren....Hwanin's Majesty....Naj's Ancient Vestige....Orphan's Call....Sander's Folly....Sazabi's Grand Tribute. I get that everybody seeks best-in-slot for end game and that almost always means rune words, but even for niche builds, are any of those sets even viable for end game? Even for an untwinked 99er, you're better off mixing/matching rares and/or crafted items than you are using those sets. I think that being able to up them in the cube would be a start in terms of helping make at least some of these a little more desirable.