Actually, I always thought it was good of Blizzard to have as one of the in-game tips "Invite your friends to Azeroth, but make sure to spend time with them in the real world too!"
The cynic would retort that they said this and then did nothing...
They did build in a rest mechanic where you became rested by spending time logged out which then increased your xp gain. It was at least a nod to playing casually.
They even added a raid finder which IMO is the biggest consession to the casual player. At one time you needed to be part of an active guild and spend a lot of time in game to see all the content. Now you can queue up and while there are harder versions of the encounter the only advantage is loot that helps you climb the treadmill and bragging rights not content.
The cynic would retort that they said this and then did nothing...