Simplicity, or what I prefer to call "cleanness", is an enduring type of design - it is not a single style like "modernist", unless you consider Shakers and many even older vernacular styles modern. In web sites designed to inform rather than entertain, simplicity is a must, and even then they are still not very good at informing. Anything that gets in the way of that is bad. Buildings are functional, but the problem with the post's comparison is that all the gingerbread and painting on a building is orthogonal to the function of a building, where on a web site any added ornamentation directly affects its usability.