Until you experience a lack of advertising, it's hard to imagine quite how gray and boring and non-vibrant a city looks without it. Turns out billboards and panels full of dramatic movies and TV shows, beautiful smiling faces selling makeup and phones... actually add a lot of character to a city and make it feel like things are happening and going on.
Imagine if books no longer had graphic covers anymore, just all solid gray and beige and black covers, and you walked into a bookstore. It feels kind of like that.
If you're going to get rid of advertising, at a minimum you've got to replace it with something -- like a lot of murals, like murals everywhere. (The Bushwick neighborhood of NYC has some areas full of street art, which works pretty well.)