I never thought Watchmen would make a huge gross because the story itself isn't exactly accessible to those who aren't already comic fans. And especially if it was going to be done 'faithfully', it would also highlight that inaccessibility. As it stands, it probably works better for those who already liked the comic, rather than those who are being introduced to the story for the first time or who are less familiar.....and the latter is very important when it comes to box-office returns. You didn't have to be a comic fan to really enjoy BB/TDK or Iron Man....but I think Watchmen required more inherent appreciation of its source material to really work well.