Even though more software is self-serve and provides zero-day value, the biggest enterprise customers still need the Sales & Marketing machine, from front-loading marketing which generate leads for sales people/sales engineers to customer success, etc.
For the longest time, the guys driving the best cars coming out of Oracle's parking lot were the sales people. That's changing, but not as quickly as we expect.
As a point of comparison:
Box R&D: 37% of revenue S&M: 138% of revenue
Salesforce (based on last SEC filing) R&D: 15% of revenue S&M: 53% of revenue
Oracle (based on last SEC filing) R&D: 14% of revenue S&M: 21% of revenue
Interesting exception is Workday (based on last SEC filing) R&D: 39% of revenue S&M: 42% of revenue
This is still a winner-take-all business because a typical enterprise customer is still 2-3 years at the minimum (depends on the product; ERP tends to be much stickier). Box is encouraged to spend expensive investor capital to focus on growth (and in the process, limit their tax exposure).
I think it'll be interesting as Dropbox moves more towards the enterprise how much of the typical "enterprise sales" playbook would they adopt?