If a truck is going from Wyoming to KC/STL/etc, I-80 to NE-2 to I-29 is the fastest way, even with all the traffic through Lincoln. So, any uptick would revolve around other means.
Now, a trucker won't take I-70 through western Colorado unless absolutely necessary, so the only issue would be: I-70 west to I-25 north to I-80 west, or I-70 west, to I-29 north to NE-2 west to I-80 west. Eliminate Lincoln, and that becomes the better way through.
Nebraska's stretch (and Iowa's) of I-80 are overloaded. Forget traffic counts, drive the road sometime. The problem isn't volume, it's the truck traffic. I-80 is a crucial shipping lane for points east and points west along the middle of the country. And from Joliet, IL west (aside from cities), it's two-lanes each way until just east of Sacramento.
Sure, the Nevada, Utah, Wyoming stretches are less congested, up until the I-80/I-76 split in Big Spring, Nebraska, the traffic chokes the road.
Sykotyk