As others have stated, it's all about the Benjamins. Back to back weeks against SEC opponents is pretty ridiculous, but scheduling with FBS (and SEC schools in particular) is pretty standard for OVC football schools. UT Martin started doing that type of scheduling around the 2006 or 2007 season. From the FCS team perspective, it's a great revenue producer that also figures into recruitment in a variety of ways. First, it allows for facilities upgrades like football operations buildings, improved playing surface like good field turf, and better weight rooms. Secondly, it gives players that were considered inferior or not worthy of FBS scholarships a chance to play in a large venue like Neyland in front of a lot of people. If they play well, people notice. It was only last year that UT Martin got a win against an FBS team, albeit a very weak Memphis team with a new coach. Just playing hard and keeping the score close can be quite an accomplishment for a school that size that is allowed just 63 scholarships versus the 85 for FBS. No FCS teams schedule these games with the expectation of a win. If they pull one off, it's obviously a great thing for them but is pretty rare. Just an FYI as an example here's what UTM's FBS scheduling has been and will be for the next few seasons that have been announced.
2005 - Arkansas State
2006 - Ohio
2007 - Southern Mississippi
2008 - USF, Auburn
2009 - Memphis
2010 - Tennessee (easy win... You're welcome Dooley)
2011 - Mississippi State
2012 - Memphis, Northern Illinois
2013 - Boise St., Memphis
2014 - Kentucky, Mississippi St.
2015 - Ole Miss , Open date that will probably be another money game