As an ISU fan that hasn't missed a home game in 15 years, here is my list on important wins this year:
#1 Oklahoma -Haven't beat them forever
#2 OSU
#3 TCU
#4 Baylor
#5 Texas
#6 Kansas State
#7 West Virginia
#8 Iowa
#9 Texas Tech
#10 Tulsa
#11 Kansas
Even though I think Texas Tech may be better than Iowa, I'd still rather see ISU beat Iowa. I still don't know how good WV is but I'd like to get the first win over them. This is just my take on level of importance.
If I was a hawkeye fan I would probably only put Western Michigan, Missouri State, and possibly Northern Illinois as games that are less important than ISU.
I think part of it is the upset factor. I don't think fans on either side will be surprised if the other team wins. On the other hand I would be extremely shocked if ISU beat a team like OU and I'm sure Iowa fans would be surprised if they beat Ohio State.