Dave, I agree with most of what you say, but I doubt very much that eBay would ever adopt a practice of extending the bidding deadline based on no activity for 60 seconds (or whatever interval) after the listing has expired. True, that would largely put AS out of business except for some of those auctions ending at an ungodly hour. But imagine the additional burden that would be placed on eBay's servers. Incredible -- tracking many thousands of auctions as they close and determining which should be extended and for how long, registering new bids as they come in, then timing 60 seconds...no way they would be able to do that without bringing a lot more expensive servers online.
And there's another twist to such a rule: snipers are sometimes the only bidders on an item they've "discovered" and kept a secret from "followers." Those items would go without a bid if it weren't for the snipers. EBay would get its listing fees but nothing else. Thus, it would cost them money in that way as well.