the interest in Iowa basketball didn't fade over a year, and neither will it be built back in a year. You are comparing it to Indiana, where their fan base and students grow up thinking that IU hoops is a big deal and when they become students they clamor for the chance to get a student tickets because it's the place to be. Not the case at Iowa. As you mentioned, IU fills their arena even for late night games against bad teams.
But even in the "down" years Indiana has had since Knight left, they will have Big 10 titles, Sweet 16 and Final 4 appearances in that time (through Mike Davis, Tom Crean, Sampson, etc.). Iowa has none of that spanning the lifetimes of the students who are on campus now. The last time Iowa won the conference was long enough ego that current students' parents were kids when it happened. It will be 23 years in March since Iowa made it out of the first weekend of the NCAA tournament. Yes, there have been some nice moments and players in the ensuing time period, but the program as a whole's biggest moments since then were winning 2 Big 10 conference titles under a coach the fans would just as soon forget. No gimmicks or other things are going to fill up Carver consistently until Iowa wins something.