I think mray is basically right about the gamification of entering developer mode on Android. Making it seem like a game (it has little "almost clicked enough to unlock!" game elements) makes it seem ok that it's not discoverable.
Which hides: You have to know about developer mode to find out how to enable developer mode. If you are not in the in-group, developer mode is not for you. If this was not Google's intent, they would make the feature discoverable.