I expect they'll open things up more as the season goes on, and as they face tougher opponents. I think they knew yesterday was going to be a low scoring day, and the minimal risk approach made sense. It would be nice if they would make better use of Mike Williams and the TEs in the red zone, it would add one more angle that the opponent has to defend against (maybe opening more room for the run / screen calls they seem to love in the red zone so far.)
It is very encouraging that the Bills were able to sustain drives all day yesterday, with only 1 3 and out (at least prior to the 4th quarter when they were just running clock.)