Wal-Mart has basically ensured it will be profitable. The convenience of it is what drives it. The flight is only going to be about three and a half hours and will feature a light meal of some sort. It isn't really much longer than other CRJ routes of the past like PHX
Fayetteville may be a "small town" (it isn't really) but the level of traffic is amazing. It is tied for American Eagle's largest outstation (with Wichita I believe). Big business in the county is the draw for the airline service. I believe Northwest Airlink just added XNA
service and Delta Connection is adding more as well.
Sure, they could connect, but the demand for a non-stop is there so why not run it.