It's good for FeaturePics, because they get traffic and inbound links to their website.
It's good for bloggers because they get free images, even if it links away from their website.
It's good for contributors because they get exposure for their portfolio.
My opinions:
It's a clever strategy from FeaturePics as they stand to benefit more than the other two groups. If it works it'll increase their traffic, search engine rankings, sales and contributions.
But! I don't think it'll work. It's aimed at bloggers who currently steal images (says so in their PR), but I can't see the incentive for the blogger to use it rather than steal. Bloggers are too small for copyright holders to chase and few have any money anyway. What's the appeal of a "legitimate" image when there's no downside to stealing one that doesn't require an outbound link?