A few points:
1. You have to love guys who don't live in the city, county, or even state proposing these things.
2. I'm pretty sure I've read a number of times that in terms of real money, the McCaskey's are the poorest out of the owners of the NFL (I understand nobody is shedding a tear for them), so that means they can't afford to build a stadium, which means.....
3. The taxpayers would be on the hook, and that wouldn't even begin to factor in the sweetheart deals the McCaskey's would get on property taxes and the like.
4. Arlington Heights and Rosemont are not attractive locations, and you voluntarily give up one of the great views in the NFL. Oddly enough, Gary would work in this regard.