So, anyone that has had reasonably competent parents were told that life isn't fair. You take what you have and make the best of things and with hard work you can turn lemons into lemonade. Truth is this... Apart from Nebraska there hasn't been a National title in the B1G West since the 1960 (Minnesota). The muscle of the B1G has always been Ohio State & Michigan and since 1991 Penn State has been among the B1G bullies too.
My proposal is simple swap Sparty and Illinois. So the divisions will look like this (arranged by stadium size)
East......................................West
Michigan (107601)..........Nebraska (86047)
Penn State (106572)..........Wisconsin (80321)
Ohio State (104944)..........Sparty (75005)
Illinois (60670)............Iowa (70585)
Indiana (52929).......... Purdue (57236)
Rutgers (52454).......... Minnesota (50805)
Maryland (51802)...........Northwestern (47330)

A few points:
1. The B1G East would still be top heavy but less so by moving Sparty giving the other schools in the East a better chance at making a bowl annually.
2. By moving Sparty, the B1G West becomes the deeper division with practically every team in the West having a legit shot to win the division.
3. Sparty had legendary games with Nebraska & Wisconsin during the legends and Leaders years and those games could quickly become meaningful again.
4. The B1G 3 would still be pulling ratings in the New York to DMV corridor playing Rutgers and Maryland.
5. Sparty recruits the heck out of Chicago and playing Northwestern annually only helps those efforts.
6. The league stays mostly geographic with with the 4 Easternmost and 4 Westernmost schools playing in their logical division and splitting the states with 2 schools per state.
7. Obviously you'd have locked games for Indiana v Purdue, Michigan v Sparty, & Illinois v NU as all 3 rivalries would be split between divisions.

You all will notice that my focus has been heavily on Sparty because they are a program that along with Nebraska has the highest ceiling. They live in the shadow of the B1G 3 and need the change and in neighborhood to realize their potential and become the National power that they were in the 60s in the Wild West.