There are definitely large swaths of "McMansions" built in the way you describe, but I don't think it's representative of the entire market by any stretch. Many newly built houses (especially in the Northern parts of the US) are using insulating concrete forms that should last hundreds of years going forward (they're moisture, pest, fire, earthquake, resistant). Several close friends and relatives have built new homes with this method.

http://en.wikipedia.org/wiki/Insulating_concrete_form