It does raise a good point that midnight premieres of heavily- anticipated movies could potentially make prime targets for a terrorist attack.
Loads of people (I was at the midnight premiere of 'Dark Knight Rises,' and my theater had at least 3 auditoriums used for it, all of which filled to capacity) crammed into a tight space, with no more than 2 exits (The main door, and usually an emergency door), and movie theaters of course have little to no security compared to airports or train stations. Theater owners should maybe start exercising some more precautions for such premieres, maybe hire some security guards or get a metal detector or something.