This is the right move. Great brands have a logo that can be reduced to one color, not only for faxing (as the blog post mentions) but for embossing, stationery

This is the right move. Great brands have a logo that can be reduced to one color, not only for faxing (as the blog post mentions) but for embossing, stationery, signage, and many applications that would be overly costly when printed in multiple colors. The change happens to coincide with the "flat" trend, but I see it as a necessary evolution for a brand that has grown into the mainstream and requires consistency across different media. Of course the logo itself leaves something to be desired, from the genericness of the concept to the strange and inconsistent perspective of the flaps. But remember, it's not just a logo, it's also an icon that sits in your dock or toolbar. As a software company it makes sense for Dropbox to have a logo that can also be a functional and iconic UI element -- another reason why 1-color makes sense. Dropbox much like Google acquired its customers through utility, not by having a great logo. It will be a hard fought battle to make "the box" symbol synonymous with Dropbox, but if they can own it, it's certainly a powerful mnemonic.