The photos are CC licensed. I think they plan to own the algorithms on top extracting value from the photos. But, I totally agree that there should be simple DB download.
The strange part is that while their legal page confirms the CC license [0], the homepage specifically says "All photos are free for personal, NGO, and educational use." which doesn't imply the same freedoms. Sounds like to me that they're not being completetly honest about the license.