I don't think it's an Iowa issue. When we had 8 conference games, we pretty regularly played a "similarly situated" program. I think an issue today is that a bunch of teams are just completely unwilling to play more than 1 decent P5 opponent in OOC play. The coaches at places like Texas Tech, Kentucky or Tennessee don't want to play two or three P5 games because the coaches know that in the history books, it's better to go 7-5 or 8-4 with some cupcakes than to go 6-6 or gasp, 5-7 with 2 OOC losses.
Another huge problem is state politics. South Carolina has a bunch of schools with football programs, like Wofford, Furman, Clemson, SC, Coastal Carolina, Citadel and Charleston Southern. Maybe more that I can't think of. And most of those schools have politically connected guys who want to see Clemson and SC rotating games among the smaller in state schools to subsidize their athletic departments. So Clemson has scheduled Wofford this year and Furman last year. If they replace them with a program like Iowa, Clemson doesn't really make any more money, but Furman and Wofford would lose a huge chunk of money. As football costs go up, those small programs become more reliant on getting P5 games and political pressure rises to schedule someone like that.
Look at Iowa's schedule from 1981. The OOC games were Nebraska, UCLA and ISU. In '82 it was Nebraska, ISU and Arizona. In '83 (when the conference went to 9 games) it was ISU and PSU. Those schedules are awesome, but I just don't see them coming back barring a NCAA mandate to play more P5 OOC games, which given the political landscape and cost pressures on the small schools, will go over like a wet fart in church on Easter Sunday.