A bigger reason why Atlanta doesn't cover the spread is due to coaching. In most cases once we have a lead whether it be 1 point or 100 we go into conservative play mode and not kill mode.
I hear you. Personally, I think a run offense is conservative by it's nature.
The only reason I could think of it being aggressive is that we get huge chunks of yardage (huge is relative here) with Dunn up the middle. We throw deep 3 times per game (and Vick usually keeps these out of bounds along the sidelines. Not effective for yardage, but effective to keep the D honest and keep away from the turnover).
I would like to see the Falcons get a lead, and then try to open up the passing game more. Just to get Vick some more game time experience for when we'll need him in the playoffs. It might keep a game close (or even lose 1), but we'll need the experience in the playoffs.