You don't want your farm team in your own back yard.
Having a team in Chicago actually makes good sense as it means if we have to call up any of our contracted players its not the case that they are flying the whole way across the continent and means no matter where the canucks are they can get hold of their players.
hypothetical example - AHL team was in Abbotsford - canucks were on the road in the south east - could we get a player there in time on short notice. However with a fairly centrally located team this doesnt become an issue.
how about when the Canucks are playing at home, which is 50% of the time? Instead of going all the way from Chicago to Vancouver, they could just get to Rogers Arena in less than 2 hours without any time zone changes. Having the Canucks farm team in Chicago of all places makes little sense.