While I don't think automated buyer feedback is a good idea, there are ways around the primary issues being discussed here. For example, just like sellers, a buyer needs to opt in, with I guess the main parameter being it's left automatically at the end of the 60 days (perhaps there could be some other criteria, like no messages post-sale, no disputes open, and the ability to exempt purchases from auto-FB).
But, because of that, at the end of the day to make the idea feasible for most, it would often require just as much participation from the buyer as leaving FB does, so it kind of defeats the purpose. The real issue is that there's no basis for an auto-FB to be left. Sellers can choose to leave auto-FB at two main points in the transaction; when payment is received or when buyer FB is received. What are the equivalent points for a buyer - when FB is received, that won't work for auto-FB, especially if they received auto-FB for paying, or when the item is received. Again auto-FB doesn't work here because simply receiving the purchase in no way reflects the transaction experience because from the buyer's perspective, there's a lot more to evaluate.
Auto FB wouldn't help future buyers, either, not those looking up FB left for specific items anyway.
The only change I can really see of being as close to this and of any benefit to buyers and sellers alike is the introduction of a transaction count. eg 5000 items sold, 4000 FB received, then buyers could see maybe the 10 people who left negs is actually 0.02% of transactions not 0.25 (not the most drastic example, I know, but you get the general gist hopefully :8} ).
