It's almost become the norm that big AAA titles are revealed very early in development so as to generate a lot of buzz before release. This inevitably leads to delays and graphical readjustments, an issue that has been plaguing the industry as of late.
Bethesda, however, has been turning the tide a bit with the unveiling of Fallout 4 just days before E3, with a scheduled release date of November 10.
Pete Hines discussed the strategy with Games Radar: "We felt like we could. If we didn't feel like that was enough time to generate the excitement that we expected and the interest that we wanted, then we would have announced it earlier. So part of it is because we felt like it was a big enough title that we could get away with it."
Hines also said, that one major reason behind the close nature of the announcement, is the development: "part of it is getting the game to the point where it's all done enough to be able to show so much of it. We're pretty close to being done, which you have to be if you're going to ship in five months."