Bornakk has since came out and clarified the changes a bit, and provided a bit more detail. Most interestingly is that this change was intended for Patch 3.3, and was accidently applied to Patch 3.2.2. I'm not really sure how such a significant change could accidently make it in, but there we have it. From Blizzard's mouth to your ears.
It would make sense that the change be applied in Patch 3.3. Cross-server instances are coming in Patch 3.3, and that's going to help leveling a ton. Think of how easy things will be if you just want to chain run dungeons at 1 a.m. for a few hours. That speed and leveling agility would help offset the XP nerf contained in this sudden AV change. But as it stands, we'll have to wait a few months to allow for another quick level mechanism to be put in place.
The other part of the change that was clarified is exactly what happened with the brackets.