It will be good if you can make the Ratings given by a buyer. Currently, Seller can see only the feedback statement and the sign but not the stars. This helps Sellers to understand where to improve by themselves. And take measures while dealing again with such Buyers, Buyers from those areas. Ex: if a few of the Buyers from a particular State/City are giving low Stars for shipping; then Seller will easily understand that he needs to change the courier company to ship to those areas.
The advent of Seller Standard to assess the Seller account basis rating; instead of mere neg/neu feedback count is an appreciable move.
Still, you need to see manually before acting on the Seller account like suspension/termination and also held the account manager or some followup executives be responsible for the inactivity or quality of a Seller. This way you can improve quality Sellers/sales/income/good salaries.
Also, good to reintroduce star rating for Sellers to be able to give to Buyers.
Ref: http://forums.ebay.in/thread.jspa?threadID=500008502&tstart=0&mod=1300855392714
Regards