Not sure how much local traffic is part of the mix in either direction. Lonoke sits a 20-minute drive from McCain Mall and remains a backwater — and I'm rooting for Lonoke to prosper. "Small town charm" runneth over but hasn't helped Lonoke much. An I-40 expansion might help, but there is zero development there.
It'll grow eventually. Most of the current growth is west, southwest and northeast in the metro area, but it's only a matter of time before land values dictate that it's turn comes.
We have a similar issue in Columbia, SC. All of the growth has been west, northwest, and northeast. Very little to the south or southeast down I-26, closer to where I live.
Anyway, I agree that they should try widening a section of 40 in the middle, around the White River and Brinkley, as relief. Here in SC, they’re finally nailing down the details for widening I-26 b/w Columbia and Charleston, and I think they may widen a relief section in the middle first, near I-95.