What’s the aversion to downtown area Chicago incalls?  In the past there were lots of options (agency / Indy) but now it seems less so.  

My guess is that many of the mongers with disposable escort money, who used to 'work late' downtown, now manage to work remotely some or all of the week.  Add to that the visiting mongers flying in and out of O'hare, and you have a shift in the market.

Can't speak for agencies since I don't really use them, but for indies, I suspect rent's a factor. Rent's been continuing to go up quite a bit in River North and Streeterville since the whole "Escape from the pandemic"  thing ended.  
Hotel rates are also up. And from what I've heard, providers see fewer clients these days because clients can't afford the visits. (I know from my own experience that I've been seeing providers less frequently than I used to.) So I think it became a matter of whether it was worth the cost to maintain an incall in the downtown/Near North Side neighborhoods.

I sometimes offer incalls in downtown depending on availability, usually clients have their own locations and hotels for me to arrive to

I keep testing out downtown incall (Monday!), but so far it just doesn’t book up nearly as well as the suburban locations. That does seem to be a good number of WFH types on their lunch breaks.

I have only stayed downtown (Magnificent Mile). I felt very welcome there - so many amazing new friends. I'll be there this coming week 19-25 October. Side note - on one of my future visits, I do plan to at least split some of my time in Schaumburg or at least near O'Hare which is a little bit more accessible for those in the burbs. I like downtown but I actually got some emails complaining to me why do I only stay downtown and not the burbs. I'm diplomatic so...  

I've visited Chicago dozens of times and I've mostly stayed Downtown. The Loop and River North seem to be convenient and centralized areas for suitors who commute from the suburbs. And there are endless options for sightseeing and attractions so Downtown is my preference.