Um, pirates usually have a defense force at their base above and beyond their raiding force... If that wasn't there, something may have been wrong.
That said, I agree that having base defenses instead of a mobile force would make a great idea (especially if they're properly set up in a tight cluster around the base, with repair centers and hangars...).
I don't care about defenses, just that they never run out of ships as long as their base is there.
