Not everything, but North American cities need a lot more skyscrapers. Instead most North American cities sprawl.

Density increases innovation. Density decreases travel carbon emissions.

I don't know about North America, but replacing everything with skyscrapers is simply not the least bit desirable in the vast majority of city centres in Europe, for example.

A city of skyscrapers would also make a pretty dystopian city, the way I see it.