Yeah, its all risk no reward for ISU\Iowa. There's a bunch of reasons almost no power conference team schedules ongoing home and home games with in-state midmajor teams. Its not just ISU\Iowa being "weak".
If you play them, you play teams that generally are good enough to be a threat, but not good enough to be good for your resume (and awful on your resume if you lose). And then you add the intangibles that don't show up on the team sheets but absolutely play into the games, including the familiarity effects of an ongoing series vs random one-offs you have with other lower-level teams, as well as the emotional edge from a rather one-sided "rivalry" that the lower level teams benefit from.
Even more importantly, there's simply the math of the scheduling and how many home games the program wants to have to keep season ticket holders happy. After you subtract the P5 games we generally schedule (conference, iowa, various inter-conference challenges, random home and homes we've scheduled like Oregon State) a few warm up games to start the year vs nobodies, and the neutral site tournaments, there's really not room for giving up an additional road game. And even if there was, Iowa State would benefit more from scheduling an additional P5 home and home than a home and home vs drake or uni.