What I've found on this blog is that many people can't comprehend that there are benefits of density (there are downsides, too, of course). They associate it with either urban ills, or the lower rent version of suburban development which tends to incorporate many negatives of density (smaller lots, etc.) without any of the benefits (walkable communities with retail, etc.)
In many areas, desirable dense areas just aren't an option for people. More than that, they don't have any experience with it so when they do come across it they find it aesthetically weird.
Still, as Kunstler is fond of pointing out, people do spend lots of money to go on vacations in places which have the kind of walkable communities we're talking about (resort towns). They just don't choose to live in them, or they aren't available as an affordable option.