It's always been that way. Individual accounts make very little money compared to enterprise accounts. Individual accounts significantly contribute to mindshare, but don't pay the bills.
Dropbox and Box have recently been named as Leaders by Gartner in their magic quadrant (normally reg-walled, but pic in this recent article [1]). Microsoft and Google have been named as Challengers.
Dropbox actually runs a pretty innovative shop [2] on a technical level. For the enterprise, Google and Microsoft offer basic run-of-the-mill storage bundled with their respective office-and-apps suites, while Dropbox and Box have a similar approach of offering APIs to make it possible to create addons or apps that integrate with the datastore or individual documents.
In a way, this enables line-of-business apps to be built that use Dropbox as backend storage and operate on documents stored in Dropbox, which has the capability to challenge a Word or Excel-based workflow.
[1] http://www.businessinsider.com/gartner-enterprise-file-stora...