The semi-finals are currently scheduled for December 31, 2016. That's a Thursday.
Because they feel they're likely going to lose potentiall viewers to the main network New Year's Eve countdowns (along with New Year's parties, etc), ESPN wants them to move the games to January 2 of that year, which is a Saturday.
The Rose and Sugar Bowls have a contractual requirement to be played/shown on New Year's Day, which is Friday next year. The Orange and Cotton Bowls are scheduled to be next year's semi-final games, also.
Since ESPN has the rights to be the only one showing all of these games, there was not really any way to begin with that they could plan to air all four on the same day that Friday (it took from 1pm until around 11 pm - I think - to air and analyze just three this year) without starting to air one was early as 9:00/9:30 AM or as late as 11:30pm/12:00 AM.