I feel that sound is a big part of it too. European buildings tend to be a titch bit better about this, but American ones are downright terrible. I'd love to live in a apartment building for a long time, but the sound is what gets me. I can't play my sound as loud as I want, I can't stand other people ignoring that the walls are paper thin, I hear every toilet flush and chopping of carrots in the building. If you can find a way to really dampen the sound, then I feel a lot of people wouldn't mind the high density quite as much.
That doesn't have to be the case... I live in a large apartment building on a high floor, and I rarely hear my neighbors. Good walls and smart design go a long way. Granted, this is a fairly new building that is a bit expensive, but my point is that noise problems in high rise buildings aren't inherent to all large buildings.
This is honestly one of the big things that turns me off of high density here. I feel like I am losing privacy and having to walk on eggshells constantly to avoid pissing off my neighbors.
