Been in the start-up situation twice where it's only 3 of us at the start and no idea how long we have to survive on a minimal budget.
Of all the services we used, Dropbox by far asks for the biggest and completely blind upfront commitment.
We just need the service Dropbox offers (and preferably from Dropbox, since that is so ubiquitous it makes it easy to use with third parties and integrate with other services).
But we can have either individual accounts (which doesn't scale, and doesn't have the convenient team-features) or commit to the whole $795/year and hope we'll soon get to the point where the benefits outweigh the costs.
Dropbox for Business is an all-or-nothing package-deal with 3 separate benefits (features, volume and accounts) which cannot be purchased separately even though most clients only need one or two in limited quantities. And to top it off it's an upfront whole year commitment.
It's dramatically different from the pay-per-use proposition of any of the other SaaS products we use.
I've done the "what do we want to get started" math twice in the past few years, and Dropbox for Business stands out like a sore thumb.