Guess they just figured that people would mainly care about the music, not the cover (heh, they were wrong...
), so they saved the really good shots for the calendar, which is obviously only about the pictures.
For those who are still sad about S/S.... Would you really rather have the water pic in place of the cover, and then the cover in place of the water pic..? In other words, it could be worse: you could have a giant S/S picture staring at you for two months instead of that gorgeous water one.
