A good reason for start-ups to target Business-to-Business over Business-to-Consumer: Businesses like to pay for their technology.
Another point, made in this post is that if you can bill in advance, the effect on your cash flow is very marked. It is, perhaps, possible to bill consumers in advance but it's a great deal easier with businesses.
As a combination, the case for creating a B2B product is compelling.
Businesses always expect to pay for their technology. They see it as a cost of doing business and, in many cases, of gaining competitive advantage. My experience is that businesses actually prefer to pay for their technology as it makes the supplier more accountable and establishes a clear contract between the two parties.