I think a lot of it had to do with what a sudden and unexpected change it was, unlike Powerhouse, which they more or less eased into by gradually transitioning from Checkerboard. Also, to me at least, Powerhouse is what really made Cartoon Network what it was, and really brought the personality and identity to CN that was somewhat lacking in the old Checkerboard era.
CN City, on the other hand, felt like they were suddenly trying way too hard to seem more hip, modern, urban, and somewhat edgy - it didn't even feel like CN to me anymore. I will admit, not a whole lot of the shows really stood out to me by then either . . . I also kind of felt like CN was suddenly placing such importance and emphasis on their new shows that they never really did with their older shows - like I remember what a big deal they made out of KND, and how they immediately treated it like it was their biggest hit they ever had (maybe even bigger than Dexter or PPG).