* wow that got yanked quick, glad I jotted down some notes
a society where life had become very difficult, the urban environment had become a trap for the people. So started with very clean design concept then successively layered on top an accumulation of details and repairs and extra pieces of equipment that weren't the original equipment idea, and achieved this fixit it because it has to run which is the whole visual flavor which is the essence of the film, so it isn't a shiny futuristic society it's a society where the supply lines have broken down. the street level became like the sewers the underside of the city being trapped on the street was not only just unromantic but a thoroughly nasty way to spend your life because the street is just a service access to the upper city, Decent people didn't live below 40 floors above the street so you get an accumulation of detail of vent pipes generators and left over kind of society that your forced to live with because you can't afford to go up. It takes a trend from the current larger urban centers and accelerates it and charicatures it makes it more brutal and more glamorous at each end of the scale.
*found on animation