You're selling Chicago's musical heritage a little short there.
Muddy Waters?
Shadows of Knight?
The Association? (maybe Windy and Up Up & Away were too schmaltzy, but Cherish is the 2nd most radio=played song of Rock and Roll after You've lost that loving feeling.')
The Buckinghams (5 top 10 songs)
Chicago – CTA Vol. 1 and anything before Kath checked out is still insanely great, and I can stomach most of their stuff through XI or Hot Streets. Once Cetera decided he WAS Chicago and Lamb, Pankov, and Co. let him do it they were officially musically irrelevant.
Buddy Guy?
Liz Phair?
Urge Overkill? - A lot of folks didn't think much of them I know but I liked them.
Pumpkins?!!?
I don't know, there are some pretty good musicians/bands spanning 6 decades in that group.