Back in 2009 when air travel had taken a dive AA was doing West/East Coast flights to FRA through ORD for about $300-$325 ai. The route was great for MRs because there was about a three hour laspe between the a/c arriving and departing. On the two trips that I did the AC at FRA was full of MRs. The staff was amazed at first with so many paxs coming in and requesting a shower.

Like others have said only really cheap fares you will see MRs. There are flyers like me that may take a trip because of a low fare, although not a MR fare per se, but its also to visit the destination. Most would consider a true MR as a situation where one is flying only for the EQMs and coming right back, never leaving the confines of an airport during the trip.