It was founded by Mitch Kapor. I think he knows a thing or two about starting companies...
That would seem to suggest that they might have thought about revenue a little earlier in the process and I have a feeling that with hindsight Mitch Kapor might agree.
So, the situation is this: we have a product lots of people want. The naive business model (freemium) won't work -- a simple back-of-the-envelope calculation shows that.
What do you do? Go forward building a very popular product and look for a business model, or quit because you can't think of how to make money from day 1?