I think ciV has plenty of depth. The problem is not that the game is shallow, it's that the game is tedious. Once you know the spastic AI will war with you randomly, it is never a surprise. Once you know that the AI cannot competently defend itself if you attack them, there is no suspense, no fun. Once you know how to manipulate the CS's and the resource trading, there is no need for even the barest economic infrastructure. If one plays to win, it's no fun after the first few times because winning is very formulaic, no matter the victory condition chosen. If one plays for immersion/roleplay, it's no fun because the AI breaks the immersion by doing idiotic things.