OK, first, if they only have 100 plays it would probably be the smallest playbook in D1 college football. Also, if you feel 25 plays is enough to get you through a football game, i'm quite sure that everyone would be complaining that "i know what they are going to call every time, just by the formation". AND, they would be right. Other teams would have NU so well scouted it wouldn't matter how great they run the play, it would not lead to offensive success.
During the Iowa game the commentators actually made mention how this staff does a great job of running plays to set up other plays. Hardly "hap-hazard" in approach and recognized by people who watch film and see games every week.