I think it's because they want to get rested up for their rivalry games the next weekend.
But I agree, we as a conference should cut out FCS games altogether. We already (correctly) feast on the Sun Belt and CUSA schools enough. And maybe we could mandate no OOC games in November.
I have no problem with an FCS school in the first couple weeks of September (especially a team like North Dakota State). My beloved Oklahoma does that, but when conference games start in late September/early October, the FCS should be left to their own conference. I applaud what Missouri, Miss State, and Ole Miss did by scheduling SEC opponents this week when the "big boys" scheduled cupcakes.