Here's a thought.

While I agree that feedback is voluntary if I was in charge I'd make a few changes. For example, once an item has been sold it may be possible to create an image that both buyer and seller can input info. Maybe such things as ......

Buyer Paid in reasonable time.

Seller posted item in reasonable time.

Item was as described.

Buyer collected and paid cash as agree'd.

Those would be open to change by eBay before implimentation.

There would then be a space at the end of each line for Pos, Neg or Neut.

Then, 30 days after the auction ended, eBay could fill in all empty boxes with Pos morkings. Going on the assumption that if either party wanted to leave other than a Pos, they woulf have done so before now.

That way, every transaction would have feedback associated with it.

Just a thought