It's no different than putting in your bid manually during the last 10 seconds. Nothing wrong with it at all. As a buyer, the final countdown gives you that chance to snare a bargain. As a seller, yes it would be beneficial to extend the auction into a going going gone format to get better prices, but that also has the potential to scare away buyers.
Lets face it, the sellers are looking for the highest price possible, the buyers for the lowest price possible, and the fees aren't any worse than what you'd pay at a live auction.
The whole eBay system is still relevant and fair for all involved, and I f@&$ing love it. Within the space of 5 minutes you can own a car that you previously weren't even looking for. Last week I sold $700 worth of things I'd been told to put in the dumpster at a previous job. Instead I put them in the boot of my car, and they were all profit.