I have little doubt that's why. Hawkeye fans have lived most of their lives with very little resistance. I was outnumbered 10-1 growing up in central Iowa. As the numbers start leveling, and ISU fans become more boisterous, Hawkeye fans will start/have started to ratchet up their defenses. They truly believe we don't have the right to have pride in our team.
I think the current level of disdain between the two fanbases stems from McCarney's 5-game streak. It gave ISU fans a little juice.
That said, it's still a relatively tame rivalry if you're not a jackass. Generally, you get what you give. The NFL/WWE/Kirkwood crowd would be in full force if Gameday was in town, and that's a bad recipe because that's the crowd that goes way over the top and starts ****. 2005 in Ames on Friday night was a bad scene.