My thoughts both positive and negative-
1) This would be perfect for me. MUCH easier to get to and around. The 1-2 Sundays when there is enough Christmas traffic to matter probably is somewhat mitigated by being on the other side of 90 and 290 and wouldn't compare to the traffic cluster near the stadium on game day or when anything else is also going on.
2) Arlington is far enough from the city that it would detract from the connection.
3) It would also be a pain for people who come to Chicago for the game because they would likely need to choose between a Chicago weekend and staying in the suburbs for the game
4) Traffic - I actually think this would be better than the cluster fuck near the stadium on roads that are designed to hold far fewer people.
5) Personally I see the possibility of a retractable roof as a big deal. I currently hate to attend games in the winter. The whole concept of Bear weather seems soooo fake tough to me.
6) A bigger stadium should drive down the ticket prices on the secondary market (though single game and season tickets will go up and PSL funding may be required)
7) Hosting whatever events would be neat I guess. Not personally a big deal to me.