I just saw the guy and woman who are the primary team behind the NFL schedule, on NFLN, talking about the process. They specifically mentioned the Bills and said they knew they deserved as many prime time games and specifically home prime time games, as anyone. They said the reason we got 4 and not 5 was that we have the Thanksgiving game and therefore did not have another Thursday game. (I know that is not 100% true, since the Saints still got 5, but that was their reasoning) Personally, I am very happy with the schedule.
When discussing the schedule a bit later in the show, the hosts said they felt the Bills should have had another primetime game.