Dayton adds nothing. Why go beyond 10? The coaches don't like playing two opponents only once. You won't get more teams in the tourney. The school does not add prestige to the conference. The school will not help you the next time you have to renegotiate the tv contract. Why would you add them? Did you notice that the top two RPI conferences (Big East and the Big 12) has 10 teams each. Less garbage at the bottom leads to higher RPI. I can't think of a single good reason to add Dayton.