According to the VP of Marketing and PR for the company, Pete Hines, he thought that if the game needed more time to create the buzz needed for a successful release, they would have announced it much sooner. He went on to say that the company felt the title was big enough to the public that the could get away with revealing it much later.
Hines also admitted that it was fun to release the first trailer along with the actual release date compared to sending out a press release with a link to the trailer. That seemed to work for those that saw the trailer right away as it traveled across the social media platforms very quickly.
With larger game releases like Fallout 4, fans often worry about the possible delays that can come along with them. Hines said that they are about done with development and that gives them plenty of time to get the game out as scheduled in November of this year.