The more people talk about it, the longer it takes to get released.
Terraria Community Forums
sharkman0101
Reepicheep
Or maybe the more people talk about it the more excited you get and then it feels longer 
sharkman0101
Or maybe Re-Logic has a dedicated staff that scans the forums for whenever someone discusses the new update and informs the team to push back the game another week when something is actually discussed