E-commerce has been the fastest growing retail channel in the US beauty market, advancing at a compound annual growth rate of 24% since 2009, according to the recently published in Kline’s Beauty Retailing USA: Channel Analysis and Opportunities report. But in a turn of events, Kline observes the opposite occurring in 2014, as digital pure plays are increasingly expanding beyond the virtual world into the physical one. Birchbox, the pioneer of online subscription sampling, opened its first ph...