I think ebay having CSG validate raw cards over a certain value makes a lot of sense, given that there is so much fraud out there. However, as others have said, having PSA validate graded cards doesn't make much sense because there doesn't seem to be much ROI there. Virtually all graded cards will be genuine, and there is too much lost in the cost of shipping to make this worth it.
However, there are a couple scenarios where I can see that this will be useful. The first is the empty box scam. This is where the seller sends the buyer an empty box that doesn't have the card in it. Obviously if this goes to PSA, they would be an objective 3rd party, and say that the seller never sent the card, which would dissuade many sellers from trying this. (I guess the seller can claim that PSA lost the card.) Next is the example where the seller doesn't actually own the card that they are trying to sell. See thread for T210 Joe Jackson (
Link). Obviously, when the seller tries to send the card to PSA, that card would not be present, so it would quickly be pointed out as fraud.
I think these examples lead to the point of what ebay is probably trying to do here. Why do folks prefer to buy high value items from auction houses rather than ebay? (Notwithstanding the recent Goldin issue -
Link), people trust that the auction houses will validate that the stuff that they are auctioning is genuine, not tampered with, and they actually have it. With ebay, if you have a low feedback seller, you have no idea if you are dealing with some sort of scam, so people are reluctant to bid very high. Even if you go through buyer protection, you need to jump through a bunch of hoops, so you are always concerned that things might not go your way, and therefore, you may refrain from bidding. However, with this graded card protection, you would have a lot more faith that you will either get the card that you bid for or you'll get a quick refund without hassles, so you have more confidence to bid higher. And higher bids mean more fees for ebay (which will definitely raise fees anyway to pass these costs to the seller).