There has been a few threads about feedback here, so I'm about to add to the list.
I've only placed a couple of orders here and have only just noticed that I hadn't left feedback for my last order placed in February. (Brickshop UK which deserved the positive feedback for great communication and fast delivery).
My point is, I only realised I hadn't left feedback for them when I accidentally clicked on the "orders placed" tab.
As there have been a few discussions about the lack of feedback, maybe it is because buyers aren't aware or prompted to leave feedback. Could this be an action point on their dashboard - or a more obvious way to leave feedback be shown on their page?