I know from my feedback most of buyers compliment me on my packing and fast delivery, which has also been better than most things I have ever bought on eBay, and I bought quite a lot on there before I decided to start selling.
So I would only advocate less than positive feedback when the buyer has obviously left one star across the board or close to that, in otherwords totally unreasonable.
As far as eBay is concerned they will currently do anything that is easy (meaning cheap) to improve their image to buyers and yes their explanation of what each star is worth is extremely biased, warm and reasonable to the buyer damning for a seller.
Next they will be stating that a 4 star hotel is not worth going into for fear of being robbed, mind you the executives probably wouldn't be seen dead in less so I suppose there is some merit in that.
Ideally they would love every seller to include p&p in the item sales value, higher insertion fee and FVF, and you could still get dinged for p&p into the bargain.
Nevermind gives the prospective (because no one else comes close in the USA let alone in in the UK) competition more customers i.e. sellers