Well not EVERY team needs 7 Home games. In fact the Cyclones are only playing 6 at Jack Trice Stadium this season.
en.m.wikipedia.org
Also this year as a hypothetical, instead of traveling to Arkansas State, perhaps it would have been more lucrative to travel to Minneapolis to play the Gophers (either as a neutral game at the Zygi Dome or Dinkytown).
The Hawkeyes-Cyclones does not have to be altered to accommodate either a 1 off or 2: game series (which doesn't necessarily need to be consecutive seasons) with Minnesota and still have 7 Home games.
Heck, the Cyclones could play 8 Home games if they really wanted to make the payola work in seasons when they get to host 5 Big 12 games which seems to coincidence with when Iowa goes to Ames.
As for the attraction, it's a an additional game in which both fan bases can travel easily to attend (day trip) thus more ticket revenue. Also inexpensive, as the schools traveling parties can get take nice charter coach buses (as opposed to flying to Berkeley, CA).