I think Minecraft needs a new world type. It should be a mix between flatland and the standard world. So you can build easily on the top, and mine below the ground.
I think there should be a perfectly flat land but have it go as deep as the normal world so you can mine for ore and have spawners and mine shafts and strongholds, there could even be oceans, if there was a world like this thats probably all i would ever play on.
Yes, That would be very cool!