Think Ag trade shows and conventions. That would be one group that would likely find Ames and the proximity to a major Ag university very attractive as a venue.
For instance a quick google search reveals the National Farm Machinery Show was held in Louisville, KY last February (I know Ames is no Louisville, stay focused). The convention center it was held at had an exhibition space of 146,000 sq ft (18k sq ft more than the proposed center in Ames) and brought in an estimated 305K visitors.
Now no one is going to argue that Ames can handle that many visitors but that gives a snapshot of the impact this type of facility can have. Ames would likely draw a huge commuter population from the state and some regional and national crowds to overnight in hotels for the conference.
Not enough strip clubs in Ames for that.
They did hold the Ag Retail convention in Hilton one year and it was ok, just not very big. The other problem is you have to plan around Basketball games and other events. I know when the retail convention was in Hilton the Basketball teams were not too happy about it.