No real explanation given for the decision
Black Ops 2 fans are an unhappy lot after the Nuketown 2025 map has been pulled from most of Black Ops 2 multiplayer modes.
The map was the pre-order bonus for Black Ops 2 but no reason has been provided by Activision. Designer David Vonderhaar confirmed via Twitter though that the double XP weekend was at an end, and so was Nuketown 2025 for the time being.
You can use the map in the custom mode, as no one really seems to use that mode; so players still have at least some access to the map. However, they don’t have the access they seem to want to the map.