Over the years, I have generally defended the CFB Playoff Selection Committee's decisions. Last season, I accepted Alabama Football being excluded from the playoffs because of the Crimson Tide's dismal performance against Oklahoma. Alabama's later loss to Michigan further proved that the Crimson Tide was not a worthy playoff team.
A problem with the 12-team format is that every season, unworthy teams will make the playoffs. When, not if, the format expands to 16 or more teams, even more unworthy teams will be selected. I define 'unworthy' as teams that are subjectively not viable contenders to win a National Championship.