Do have to say, I am not experiencing the same problem. When I've requested flight following they do answer, and only say no on peak times.
The *only* time I've ever gotten flight following from C90 was at midnight on a Sunday night.
Rumor has it they've been much more accommodating recently, but only because the newbie trainee controllers are getting all the VFR's on a separate frequency to practice.
ATC will always answer, but not necessarily provide the service requested (VFR flight following). IFR they have to provide service (not necessarily honor a specific routing request).
No, and no, and no.
I've had them not answer at all a couple times. Usually they will at least say unable, but as noted above, the only off-peak time they seem to have is at midnight on a Sunday.
Oh, and they don't *have* to provide IFR service unless you're taking off or landing inside their airspace. Those of us from outside their airspace get routed way out and around so that we never talk to them. For example - MSN-LOM is 655nm. Going via the south end of the lake to stay over land is 683. Going via the normal eastbound routing we get out of Madison, via KELSI, is 731. 50nm out of my way because C90 won't talk to me either VFR or IFR except Sundays at midnight. Even reasonable routings like V177 (MSN-JVL-JOT) that stay out of the Bravo are refused.
Midnight on a different Sunday was also the ONLY time I've gotten an IFR clearance that took me into C90 airspace - And I mean, the part where you talk to them, not the Bravo itself. (Clarification: I did get cleared direct MSN from over VPZ, which took me through the Bravo at 6,000 feet directly over the top of ORD - But that's the only time I've ever even talked to Chicago Approach IFR, as normally Center will route us so that C90 never talks to us).
There were reports that C90 doesn't even know how to handle VFRs. A VFR into O'Hare was told to talk to tower who told the plane it had to talk to approach and this went on for several cycles.
Two experienced pilots, in fact, one of whom was being flown to ORD to pick up a Citation that was there. Approach->Tower->Approach->Tower->Approach->Tower, 6 different frequencies, until finally the last Tower controller called up C90 and told them what to do. (I bet it was Dean, who has worked OSH a number of times...) But, of course, this was a VFR *into ORD* which probably doesn't happen much.
Yes, I know they're busy and understaffed - But so is the rest of the world, and I've been cleared into every other Bravo I've ever asked.