Disclosure: I am a director of one of Japan's largest luxury ecommerce sites, so I feel fairly qualified to give feedback about this :)
Firstly, ecommerce + social is a really attractive combination for us. In that respect, don't give up on the problem you're trying to solve - I think there is tons of value there.
Secondly, I will echo the comments of the poster "secret" - from the merchant's point of view the risk of distraction is not one that I take lightly. I'm very unlikely to pull the trigger on implementing something like this without a lot of data to back it up. You need to work on building case studies that I can see, with statistics that show an increase in some kind of metric I can get behind - facebook activity, sales, etc. Work with some ecommerce partners or even start selling stuff yourself as an experiment, then you'll really start to understand the pain-points that you can concretely help with.
Thirdly...
I don't think the current implementation adds enough obvious value. A stream of Facebook comments is very difficult to derive ROI from. If I were to pivot, and had to keep the overall theme of ecommerce + social + facebook, I would build a set of plugins with specific use-cases that work with my store and facebook. For example:
1) a plugin that allows a user to create a "shopping list" on facebook from the products in my store. Make it fun, like a game - perhaps I set myself a budget on facebook and then my friends can vote up or down on the things in my wishlist that they think I should get.
2) a plugin that facilitates a "buy me this" feature. A user picks a product on my store and can send it to their boyfriend / girlfriend / mum / dad on facebook (maybe with a nicely formatted letter-style message) asking them to buy it for me. Maybe the purchase is incentivised somehow, with a discount if you get someone to buy it for you.
Make a set of these types of plugins, then I think you have a business. Give the most viral one away for free, and charge shop owners a monthly fee to use the whole set.
Boom.