Michigan is Wisconsin's fixed crossover rival. Not Penn St.
Penn St's fixed crossover is Iowa.
I'd rather play Nebraska every year than Iowa because of their helmet status, but I'd reluctantly switch with Penn St because I am a geography-minded individual and it would absolutely bug the crap out of me if MSU and Purdue were switched. It wouldn't even do all that much to balance the divisions. Sure MSU is better than Purdue right now, but there would still be a 1-3 split of the "helmet" schools.
The inner-outer idea that we had when they were contemplating the new divisional alignment is a compromise that I could have lived with, but the proposal of swapping MSU for Purdue is not one that I could ever get behind.
If you wanna beef up the West by adding Texas and Oklahoma, now we're talking.