The reason that eBay paid such a huge price for Skype has now become clear. There were several companies competing to buy Skype, and just before the bidding closed, eBay decided the best way to win was to place a giant bid just a few seconds before the end. (This might be known as bid skyping.)
On a serious note, it has long been eBay policy, it is reported, to not want to facilitate communications between buyers and sellers, because they will just arrange to avoid eBay fees by selling outside eBay. Either this has changed, or the “obvious” parts of the plan — Skype presence on eBay auctions, “Skype the seller” buttons and so on, are not part of the value for eBay.