If the objective is to just get to 6-6 and a minor bowl bid, then softening the schedule can certainly help in that effort.
But if the the contention is that by doing so it will strongly increase IU’s ability to ultimately field a sustainably winning program, then the argument IMO pretty much falls flat because it is not, as it relates to IU, an evidence-based argument.
If one believes the ceiling for this football program is 6-6, or perhaps 7-5, and a minor bowl game, then by all means fill the OOC with FCS and “lesser” G5 teams—but no one should expect, especially at IU, that using that approach will put the program in a significantly better position to finally become a quality program that in some, if not most, seasons has a solid chance to win 8, 9, or even 10 games.
That kind of quantum improvement requires very good, if not great, coaching. And a program can’t “schedule” its way to acquiring such coaching. In the vast majority of cases it 1) has to be bought, and 2) is usually profoundly expensive.
I’ll say it again:
Coaching > scheduling
Coaching > bowl bids
Coaching > attendance