At Disneyland, they purposely increase the estimated times you wait in lines for a ride. Why? To displace any dissapointment you would have from waiting in said line if it takes longer than the REAL estimated time, which it sometimes does. They know this could ruin some peoples daysif they are constantly being lied to about wait times as some families like to plan thier day out.
It's been a long time since I have been dissapointed by Blizzards estimated time that servers go live after a patch day, I now know to add 3-5 additional hours to those estimations for most patch days. But what about the people that make it a point to be home to play right when the servers come back up? Some of these patches are quite exciting, so I can understand if someone cuts out of work early, comes home from hanging out with friends a bit earlier than planned, ect. I can understand the frustrations and dissapointment of those players to come home only to wait 3-5 additional hours to enjoy thier hobby.
Why doesn't Blizzard just over estimate? Just tell us that its a big patch, and there will likely be problems implimenting it so don't expect servers to be back up until 3pm, or even 5pm PST. Stop setting expectations that you fail to hit time and time again, it can't be good for business. Right now you might not have to worry about that, but your failure to live up to your expectations every couple of tuesdays will definitley stay in the back of everyones minds when and if a real competitor in the market ever arises. This could be fixed with over estimating, Disney's doing well.