Peter Cetera ruined Chicago.
After Terry Kath's horrible (and stupid) demise, there was nobody to push back on the king of corny piano ballads. The band went from very interesting time signatures and horn arrangements surprising song structures to "You're the Inspiration".
I hate Peter Cetera (the musician), I can't say I hate the man because he could be a very nice guy. You know, you could have remained innovative on the bulk of an album, with the occasional scmaltz to get the radio play for the royalties. The Police pulled it off. Why couldn't you?