Robin has to monetize as many aspects of the site as possible in order to keep paychecks flowing now that he and others depend on the income.
My advice to shop owners is to realize this can be a positive benefit for you. For the above mentioned reason, It's in Pinside's best interest to bring buyers to your storefronts. Shop owners can leverage that. I'll leave it up to you guys to figure that out, but start by thinking about visitor metrics, etc... information you need to gather to maintain a growing storefront.