Just flew ATL-SEA the other day and same BS announcement prior to take off and then again in the middle. No turbulence at all. When I fly MU/KL/AF they all work through the actual turbulence and I can't remember getting one of those silly announcements on other carriers. Even on short regional flights in Europe they do a full beverage service with a snack, but not Delta. I can't help but believe the FA's are just being lazy.