Recently the trailer that was shown at Comic Con for Suicide Squad got leaked on to the Internet and then shortly afterward got officially released. The only reason that it got officially released is because the WB did not want the shaky phone cam footage of the trailer to represent the film. They actually went so far as to admonish any fan who posted or shared the footage as it was illegal and they wanted to create a special or exclusive experience for the Comic Con attendees.
Exclusives can be great incentives for people to buy or attend something, but can some exclusives be either elitist or seem counter intuitive? A lot of times video games have exclusive content based on the console the game is on, which awards people who own that console. Other people still get to play the game, even if they miss out on that one piece. It is the same thing for exclusives during pre-orders that those who are willing to put down their money early can get extra features, but anyone can buy the game later and play the same game. These are very different types of exclusives than showing a trailer only at a convention and it makes me wonder if they really do anything.