> Isn't that true of almost every flag?
According to the parent comment, yes.
True. But the flag of Illinois is rather less distinctive than many.
The Illinois flag is basically the state seal centered on a while background. And the seal is a conglomeration of standard symbols. A very similar description covers the flags of 19 other states (background color varies, and often it's a shield instead of a seal): Connecticut, Idaho, Kansas, Kentucky, Maine, Michigan, Minnesota, Montana, Nebraska, New Hampshire, New Jersey, New York, Oregon, Pennsylvania, South Dakota, Utah, Vermont, Virginia, and Wisconsin.
Because of the generic appearance, even people from the state who have some idea what the flag looks like might have trouble picking it out in a collection of U.S. state flags. So Kansas, Montana, Oregon, and Wisconsin took the same route as Illinois, adding the name of the state in large letters to the official flag design.
Now compare the state flag of Texas (pic: http://www.50states.com/images/redesign/flags/tx-largeflag.p...). The design does not exactly scream "Texas" -- although there is that nickname: "the Lone Star State". But once you have a rough idea what it looks like, you can easily pick it out from a collection of flags from the U.S. and all over the world.
The same holds for the flags of Maryland (pic: http://www.50states.com/images/redesign/flags/md-largeflag.p...), Arizona (pic: http://www.50states.com/images/redesign/flags/az-largeflag.p...), Colorado (pic: http://www.50states.com/images/redesign/flags/co-largeflag.p...), and Alaska (pic: http://www.50states.com/images/redesign/flags/ak-largeflag.p...), to name a few.
That's not the complaint against the Illinois flag; the complaint is that, even after being shown it, and being told what it is, you'd still have trouble picking it out from a row of state flags 24 hours later.
There are worse offenders than Illinois, though:
http://en.wikipedia.org/wiki/File:Flag_of_Idaho.svg
http://en.wikipedia.org/wiki/File:Flag_of_Kansas.svg
http://en.wikipedia.org/wiki/File:Flag_of_Kentucky.svg
http://en.wikipedia.org/wiki/File:Flag_of_Maine.svg
http://en.wikipedia.org/wiki/File:Flag_of_Minnesota.svg
http://en.wikipedia.org/wiki/File:Flag_of_Michigan.svg
http://en.wikipedia.org/wiki/File:Flag_of_Montana.svg
http://en.wikipedia.org/wiki/File:Flag_of_Nebraska.svg
http://en.wikipedia.org/wiki/File:Flag_of_New_Hampshire.svg
http://en.wikipedia.org/wiki/File:Flag_of_New_York.svg
http://en.wikipedia.org/wiki/File:Flag_of_South_Dakota.svg
http://en.wikipedia.org/wiki/File:Flag_of_Utah_(enhanced_var...
.svg){kind=link}
http://en.wikipedia.org/wiki/File:Flag_of_Vermont.svg
http://en.wikipedia.org/wiki/File:Flag_of_Virginia.svg
http://en.wikipedia.org/wiki/File:Flag_of_Wisconsin.svg
By contrast, once you learn one of these flags, you'll be able to identify it easily, even from a distance, and never mistake it for another one:
http://en.wikipedia.org/wiki/File:Flag_of_Maryland.svg
Ok, how is the Chicago flag any different. If you didn't tell me what it was a flag for, I would never be able to guess that it was Chicago's. How is some white bars, two blue bars and 4 red stars not "hopelessly generic?"
Without labeling, any flag could be from almost anywhere until you're told otherwise.