I may be remembering this wrong, but I seem to remember that when Beane was first hired, he stated his goal was for the Bills to be a consistent playoff contender, emphasis on consistent, year in, year out. I think he realizes that with the super bowl being a one and done tournament, combined with the randomness of injuries (January team is never the same as Sept. team), weather, officiating, and not playing with a round ball (lucky bounces), winning a super bowl is a complete crapshoot.
I think he feels that being in the tournament every year gives him his best chance of winning a super bowl (just like more draft choices give you the best chance of finding a stud-the lottery ticket model). An all-in approach doesn't seem Beane-like. The Von deal was out of character, and blew up in his face.