I think even if people did not have height restrictions they would still be plenty attractive. It's why balconies are also everywhere; people like outdoor space, and if you don't have much of a backyard to speak of your options are sideways or out.

most of the new Seattle flat roofs are townhomes with no backyard to speak of, because there are townhomes where that would be.

In my neighborhood of single family homes, the new ones are all flat roofers with little or no eaves.

since when have Americans turned down excessive square footage? see: McMansions and McModerns