Why has architecture forgotten smell?

(from "Invisible Architecture: Experiencing Places Through the Sense of Smell" - Anna Barbara and Anthony Perliss)
Richard Neutra commented in 1949 that we should devote as much attention as possible to all the non-visual aspects of our environment...surprising because this dates from a time when we would never have suspected such issues to surface, when Modernism was in full swing and the dominance of the visual had yet to be challenged.

Many reasons why there is a lack of regard for smell in architecture:

• simply that smell is invisible and can hardly be addressed or represented using the usual visual based tools of design. In order to be considered, the invisible often has to invent other media, form new expressive language, make itself visible.
• the intimate relationship between smell and emotion. Odour is a powerful vehicle for memory, evoking the emotions that a given scent had originally stimulated, bringing back to the surface pleasures or pains
• our sense of smell is extremely evanescent and intangible, caught up in the dynamic flow of time  like sound and light.