The reason for NON downtown is simple....

parking is expensive and most of all, impossible to find!

is many reasons so take your pick.

Rooms are about 2-3x what they are in the burbs for the same quality.

If you host in the loop then you are pretty much catering to city guys, most burbs guys don't even bother due to issues with parking(cost, ability to find and that sort).

LE has a very heavy presence in Chicago Proper.

Transportation, the price to get a taxi from the airport is pricey to go into Chi.  As well if local getting there and back home can be an issue as well as parking as mentioned above can be an issue.

When you have a particular type that makes it harder, because there aren't many to begin with.  Might be worth the extra time to get a room yourself and ask for an outcall or to stray to the burbs and find one who is you type if you have the time.

A lot of guys in the city can't easily get to the suburbs and are frustrated by the lack of providers here.