What irrates me most is probably how long they waited to roll out the 1.7 beta patch, because as long as it is in beta we won't see hide nor hair of Dawnguard, and if it isn't a fixed period beta then we may not even see a release date anytime soon.
Having a release date will calm a few people down, there will still be a lot of annoyed people but it is better than everyone being annoyed that the exclusivity is up and they are still in the dark.
Wait, why can't they just release it together? I don't see why they must release the patch, wait a week, and then give us Dawngaurd..