I came back to this game just recently and noticed the sheer lack of mobs in the latest snapshot and the official release up to this point. Even when I change it to hard mode there's still a lack of mobs. When I changed it to 1.6, the mobs had their normal spawn rate. I'm not sure if this is a bug or not considering this has been like this sense the start of 1.7, I just thought I'd report it though. I like the spawn rate the way it was in 1.6