It is important to remember that students are not randomly assigned to their undergraduate institutions. To the extent that the stronger students attend the higher prestige undergrad schools, we would expect the higher prestige alumni to be overrepresented in the high prestige MBA programs.
I think it is fair to say that the Univ. of Iowa is seen in a generally positive light but not on the same level of the Ivy, Little Ivy, Public Elite, and Tycoon U schools. Nonetheless, the gain in difference in perception from moving from Iowa to one of the schools you mention would almost certainly be swamped by the other factors involved in the move. So if you have a very strong reason independent reason to move you might want to do so but I would hardly base a transfer decision on it. That said, you have some strong school on the list, such as CMU that are worth investigating more closely.
In addition, don't forget that where students attended college is another aspect of class diversity. Having a student from a school like Iowa would probably be more appealing in this sense to (say) Columbia than having another undergrad from NYU.