In coaches contracts, a conference championship is typically rewarded higher than a bowl victory.
Maybe a former coach can add some light here, but the most important first step is to win a conference championship and that is the main goal at the start of the season.
Several 5-7 teams this year will play in a bowl, and none of them would like trade a bowl victory for a conference championship. Bowls are good memories and have luster, but there are just too many of them to say a bowl win is better than a conference championship.
Although there is always a cinderalla story like Boise beating Oklahoma in the Fiesta Bowl several years ago.