I guess it depends on your definition of "overproduced," but I would disagree. Nevermind and In Utero sound good, but the songs are still raw and messy. Modern rock now is impeccably played, over-compressed and digital-sounding.
I'm really talking more about In Utero, though. They were at the peak of their popularity, but instead of pushing things towards a slicker product, they were writing stuff like "Milk It" and "Radio Friendly Unit Shifter." I mean, their mind set is pretty well spelled-out in the title of that last one