Companies that typically focus on one product

Companies that typically focus on one product or service are known as "pure play" companies. It also describes a business model that is e-commerce-only.
However, a host of pure play e-commerce companies, ranging from Wayfair furnishings to Casper mattresses to Amazon Books--even the subscription box service Birchbox--have recently gone in "reverse," opening physical locations to supplement the virtual.
(1) What do you think of the future of pure play e-commerce going "clicks-and-mortar?" Why are they doing it? Is it a sustainable strategy? Or is it only suited for some e-commerce companies?
(2) Can you think of an e-commerce company that should consider adopting clicks-and-morter? @ tag them and let them know how!