Because in every iteration of the Big 8 and Big 12 conferences ISU has always been the school farthest north by a lot - and it’s especially noticeable without Missouri and Nebraska in the conference. We’ve always been “the northern outpost”.
The difference now, with the addition of WV a decade+ ago, and the recent additions of Cincy, UCF, and the 4 Corners, while we’re still the northernmost school, the conference has greatly expanded both east and west, making ISU much more centrally located in this newest iteration of the conference.