Right in the middle of one of the state's tourism areas, no less.
I grew up around Milwaukee. There are plenty of hot summer days where you'd love to go to Bradford Beach on Lake Michigan, and often it's out of the question because E. Coli levels are too high. We dump raw sewage into the lake. Nobody is concerned about Foxconn pollution.
edit: For the record, I was against this deal as soon as it was announced and still am, but not because of pollution.
That being said, it's definitely a developing area and becoming more urban. Oak Creek especially is becoming very nice. In 30 years or so, it would not surprise me if that whole stretch of 94 between Milwaukee and Chicago became urbanized.
Go take a look in the marinas in the counties between Milwaukee and Chicago. A lot of Big City money floating in those communities (and in condos/houses along the lakeside).