The auction's responsibility is to get the seller the highest possible price for their item. Sniping goes against that principle so I think that BAT's policy of two minute extensions for late bids until all bidders have maxed out is correct.
That eBay doesn't prevent sniping is probably due to a flaw in the site's code. If they were smart, they would fix it. But then, they might lose the bargain hunters who try to get that last second winning bid.