tbh: 5 weeks ago I messaged one of these guys on ebay to negotiate a better price for 4 arduino nano clones by going around ebay (I know, against ebay policy). He made a good price and I paypaled the money. No product arrived and no communication. I must say I'm glad he didn't take bitcoins. Now I can do a chargeback on paypal (hopefully they wont notice I violated eBay policy)... not possible with BTC.
Bitcoin technology contains more complex forms of transactions, for example, transactions with a third-party escrow function. We are currently not using bitcoin technology fully.
And even without that, you can have an escrow service like silkroad does. You pay SR, SR pays the seller when you say you've received your delivery. No reason why ebay couldn't include something like that down the track (apart from the fact that paypal probably would put pressure on them not to, of course).
There could even be room for someone to set up a pure 3rd party escrow service. They set up a transparent dispute resolution procedure, take a tiny bit off the top for themselves, and start working to building up a solid reputation. You buy things off ebay or whereever else, and use this well known third party to escrow the transaction. Could work.
