That headcount is part of the reason it's easier to compete with Google.
The design of the Google organization rewards micro-optimizations (use data for every decision, or else your ass isn't covered) and risk-aversion (set low KPI's and game them to get the biggest bonus each quarter).
By contrast, the design of the innovation space in general rewards peak-jumping, risk-taking, and a healthy blend of intuition and data. And it already selected Dropbox.
Don't get me wrong, the (layers and layers of) leadership at Google want to make killer products. But at the level of the lowly implementer, not only is making killer products only a peripheral concern, but those who can and want to make killer products tend to self-select out of Google.
It would be pretty tough to compete with an over 10,000 engineer company with incredible building blocks on features.