I think your last argument is absurd. For such a large state there are only 3 interstates to maintain, and you are indeed receiving federal money to do just that. If trucks are indeed tearing up the pavement why not restrict load limits?
My source for I-70 vs I-80 is living in the area and watching this happen. It snows more on I-70 than I-80, plain and simple. You don't hear about the incredible skiing in Wyoming because it just doesn't snow that much in Wyoming. It does in Colorado.
Rhode Island also only has 3 interstates! Check our total mileage and you'll see we have 914 miles of interstate, more than most states, all of which have a higher population.
Also, if you think the towns along the I-80 corridor are dependent on I-80 for their existence, you'd be badly incorrect. Evanston is popular as a Salt Lake City fireworks/gambling/liquor destination, Green River/Rock Springs/Rawlins are dependent on natural resources (oil, wind, coal), Laramie is university, and Cheyenne is government. Out of state I-80 travel has very little impact on local economies. Evanston's proximity to Utah wouldn't immediately disappear, Green River/Rock Springs/Rawlins critical oil reserves wouldn't disappear, UW wouldn't disappear, and government and Warren AFB would still be in Cheyenne. There'd be a slight hit, for sure, but it wouldn't be crippling.