As Paul points out, if all bidders were intelligent and just bidded their max amount, even if they all did it at the end of the auction, eBay (and the seller) would not lose any money because of it. Spending development time to combat this non-problem would cost money and gain eBay nothing.

But sniping actually improves the seller's take, and, therefore, eBay's because people get caught up in the heat of battle and keep saying "I can bid just a few dollars more" and end up bidding more than they would have if they were asked to choose a single maximum amount.

You can argue that sniping is a bad thing, as I would, but eBay doesn't see it that way. It can do nothing except increase the winning bid amount. If it increases, eBay gets more money. So why would they want to fix a problem that actually generates more revenue for them?

Now you can argue that the bidders find it unfair, as they do and as they should. (I actually think that the problem lies not with sniping but the associated problem of being allowed to rebid.) eBay might want to fix the problem in order to ameliorate the bidders. But what would that gain them? More bidders? eBay is not at a loss for bidders. Also, sellers would rather sell at a site that can get them more money, and since sniping creates the possibility of higher profits, they'd rather have sniping enabled. If they were to offer snipeless auctions, what sane seller would want to choose it? Going to another site that offered it will have the additional problem of fewer bidders.

If eBay wasn't a virtual monopoly in the online auction world, we might see some improvements, but no one else has even come close to matching them, and, at this point, in order for one to do so, it'll have to offer snipeful auctions in order to draw sellers. After all, if there's nothing to be sold, the bidders won't come, even if the auctioning is better.

The only solution I can see at this time is governmental interference. And I can't imagine many people would be in favor of that.