A few comments:
"Customer from Russia" - i really shouldn't single out Russia, Canadian actually gave me the most problem of all the nations, LOL; seriously.
"If not, since eBay/PayPal enticed me to buy from sellers advertising on their site with a Buyer's Protection Program, I ask for a refund and expect to receive it promptly." - I purchased a Hugo Boss belt from a US buyer last month, the picture shown clearly has hugo boss printed on it; but when i received the item the hugo boss print disappear. I filed a not as described with paypal but the seller shipped quickly to me via priority post with a tracking #, my claim was denied.
"I am amazed at the # of eBay listings that still state that the seller is not responsible if the package is lost in the mail." - i don't have it stated that way but i can understand why some seller do, it's out of frustration and loss from dis-honest buyers.
Most buyers are honest folks but it only takes a few to spoil the party. eBay "policy" is that it's the seller's responsibility for the goods to arrive, but just because ebay says so it does not mean it's the universal truth; in fact most company require you to file a claim with the carrier (ups/fedex, etc.) in case of loss or damage goods.
We have to remember ebay policy is written up to protect its' own interest and liability.