I think some "experts" are writing off Iowa early because of a perceived lack of defense and/or athleticism. They aren't necessarily wrong, but Iowa has improved enough that 75 points will win the vast majority of games. Iowa's defense will never be truly "elite" unless they pull in some more elite athletes.
And it's March Madness. People pick crazy upsets all the time because they do happen on occasion, even when there is a huge overall talent discrepancy. It's not uncommon for a player to hit 2/3rds of their 3PT attempts in one game and help their team pull off a stunning upset, but go ice cold the next and their season is over.