Though the idea concept is a great one, there are a mainly two inherent problems associated with the method of implementing it.
1. Using a credit card to make the initial payment to bid would mean non-credit card holder wouldn't be able to bid. Which would reduce the number of participants taking part in the auction.
2. There is a cost associated with every transaction, especially for credit cards. The more the number of credits and debits, the more fee the merchant (eBay) has to pay. Which would inevitably be passed on to us (The sellers) through hiked eBay fees.
An alternate solution would be as follows:
1. Just as there is Buyer SMS verification, Buyer Feedback filters etc. eBay can offer an additional Buyer filter of Earnest Money Payment.
2. Under this filter which is optional, buyers can deposit an X amount of money with eBay. This money can be transferred to ebay via, credit/debit card, online transfer, DD, check etc. The money is refundable to the buyer, at any time. Buyers can view the amount they deposited with ebay, on their account page.
3. Sellers can choose to activate this filter on their listing, where buyers account will be deducted, y% of the listed/winning bid price, when the buyer choose to purchase/win the auction for the said listed item. Upon fulfillment of full payment, the y% amount deducted from buyers account will be refunded back to buyer's account. In the event that the buyer does not fulfill payment, the y% will not be refunded to the buyer. The amount or part of it, can be used to pay the seller for loss of time and listing fee.
4. Buyers without the deposit, cannot participate in 'auctions listings' or choose 'non-paisapay payment options for Buy It Now listings', when this filter for that listing is enabled.
This is just an idea. I'm sure eBay with its creative staffs can come up with a better solution to ward off non-paying buyers.