I live in a city and I can truthfully tell you that I don't know what peace and quiet is. The 'quiet' that is to be had in cities is of an entirely different quality than that which you would experience in rural areas. The first time I visited the country I was amazed at how quiet it got at night.
Noise pollution is a legal right that we are all entitled to. Residents of Copenhagen have actually just fought for that, and the ruling left many other people angry, but it doesn't matter, because it's every ones freedom to make as much noise as they want. So no, urban areas should not repress the noise.
While it would be nice to have less noise in big cities, it comes with the territory. The problems we face are so numerous, that we have to be selective in our focus. Air and water pollution and climate change are much more pressing issues right now than noise pllution.
Urban areas should not be doing more to abate noise pollution. It is not the government's job to regulate the amount of sound made. Furthermore, the large variety of people and vehicles, even if each individual did his, her, its best to keep noise to a minimum, noise will be made. The sum of the parts is bound to be loud.