Ah but by going up to Ludington-Manitowoc-Green Bay-Wausau instead, you miss the traffic of Northwest Indiana, Chicago, Milwaukee (or Rockford if you prefer I-90), and Madison.
Look at the population difference between Detroit and Minneapolis if you take I-96 as apposed to I-94/90.
Michigan - Washtenaw, Jackson, Calhoun, Kalamazoo, Van Buren, and Berrien pop is 1,124,587. I excluded counting Wayne County since both 94 and 96 are in it.
Indiana - La Porte, Porter, and Lake pop is 771,815.
Illinois - Cook and Lake pop is 5,898,137.
Wisconsin - Kenosha, Racine, Milwaukee, Waukesha, Jefferson, Dane, Columbia, Sauk, Monroe, Jackson, Trempealeau, and Eau Claire pop is 2,609,548. I excluded Dunn County since both 94 and Wis 29 (my prop of I-96) are in it.
So going just on I-94, that is a total pop of 10,404,087.
Using I-90 between Chicago and Madison:
Illinois - Cook, Kane, McHenry, Boone, and Winnebago pop is 6,368,135.
Wisconsin - Rock and Dane pop is 648,404
Pop of I-90 segment is 7,016,539.
Total pop of I-94 with I-90 avoiding Milwaukee is 9,251,088.
I-96 + my proposal of I-96:
Michigan - Oakland, Livingston, Ingham, Eaton, Clinton, Ionia, Kent, Ottawa, Muskegon, Oceana, and Mason pop is 3,005,156.
Wisconsin - Manitowoc, Brown, Shawano, Marathon, Clark and Chippewa pop is 602,566.
Total pop of 3,607,722.
That makes a difference of 6,796,365 fewer people from I-94 only and difference of 5,643,366 fewer people from I-94 via I-90.
So tell me again why this is a bad idea? Think big picture guys.