The damage is too extensive!
Defense HQ (Tiberium Alliances) has been marked for cleanup. Reason(s):
Taking out the Forgotten Defense HQ during a raid on one of their Camps, Outposts or Bases effectively cripples the encampment from rebuilding it's units and buildings should you not take down the Construction Yard. This allows you to attack again (using the same amount of Command Points again) making the attack somewhat easier.
Failing to take out either the Construction Yard or the Defense HQ means the units damaged will regain a lot of their hitpoints and and buildings damaged get somewhat repaired.