I was born in the Quad Cities (Illinois side), and grew up in Central Illinois, and lived there until about 5 months ago (spent a couple years in Southern Illinois too)
by and large, people downstate have a pretty messed up conception of Chicago... they don't realize that 1 block in the Loop is more productive than some downstate counties.
still.... it can be said that state lines aren't typically logical. There certainly is a policy disconnect at some levels, you have a very urban area which is essentially the capital of the Midwest, you have a number of metro areas which are becoming focuses of activity for the rest of the state, and you have the gaps which are dying off...
A professor in Grad School pointed out that, simplistically, regions can specialize in efficiency or innovation.... and policies differ greatly to accomplish those goals. I don't think Chicago is failing at all, if anything higher paid professionals are moving into the city, displacing entire families of lower income workers, who are moving into inner-ring suburbs that are going to be the new slums in a few years. The projects Chicago undertakes caters to the types of businesses that want to locate there.
On the flip side, downstate areas get fed up with democratic policies that undermine their ability to attract lower wage jobs (that might still be good salaries for those communities).
The "break off cook county" proposal is suicidal for downstate metro areas like champaign/urbana and bloomington normal...
Living in Iowa, it is nice to see cities on more of an even playing field... although people here still have a paranoid view of Chicago too