If it was in the past 3 Serie A seasons, I would have agreed with you that AS Roma will beat Bologna, but with how Bologna's performance has dramatically improved, I refuse to accept that AS Roma will beat Bologna even though the bookmakers favor AS Roma to beat Bologna. In my opinion, this AS Roma vs Bologna match is likely to end in a draw, and if I were to place a bet on this game, I would play both teams to score because that is the most possible option this match can produce.
I don't know if you have watched the Bologna vs Roma match in the last 3 seasons. You are saying that if it was the last 3 seasons, then you would accept that Roma team can beat Bologna. But the interesting thing is that Roma team can't win any of the last 5 matches against Bologna. Roma team lost 3 matches and drew 2. And this season Roma team has the highest chance of winning against Bologna.
One of the reasons why Roma is considered as favorite is because Gasperini is a great coach. And with the help of Gasperini, Roma team performed very well in the last season. And it is expected that with the help of Gasperini, we will see more improvement in Roma team's performance this season. And that is why bookies consider Roma team as favorite in this match. I am not underestimating Bologna team, even then Roma team has more chance of winning this match