Now you are really going off the charts. In order for there to be an inferiority complex, there has to be an inferior and superior positioning. So on what basis is one to claim that IU is superior to Purdue in the last quarter century? During that time, IU got to the Final game - once and lost. So did SDSU.
In the past two decades, which is the extreme end of the consciousness of most fans, IU has been mostly irrelevant. Purdue has done more; not that Purdue is at the top of the mind to most, but nonetheless higher than IU. Purdue has the advantage of a better football legacy and recent performance. which helps it. How many primetime Saturday night home games has IU had on national TV in the fall?
Last night, I was watching the NY Yankees-Cleveland game. During the broadcast, it was noted that yesterday was the anniversary of the end of Lou Gehrig's playing streak. Given the unfortunate lack of general education in the USA, there are very few people who know who Gehrig was or what he did - and he set Hall of Fame records. So to suggest that the IU brand has real significance these days is silly.
I believe that you live in the IU/Indiana media bubble. I live elsewhere and come from elsewhere. As such, I get exposed to more. If you want to claim that in Indiana, IU gets more media props, I would agree. However, outside of that, there is no way that is true.
In sports, football dominates basketball in viewership and earning power. IU's football legacy is very, very poor. IU is one of the few schools where the BB coach historically makes more than the FB coach. Kansas is another. Purdue is good to very good but not great, especially recently. However, Purdue has better academic rep and the astronauts so that raises place in minds. RMK is gone and with him went the national presence of mind.