Regarding the 10 more blocks extension I think that is bit too much. It's an hour and a half, nobody has that much time to waste bidding, IMHO even extending one block at a time my lead to too long auctions and bidders losing interest, but it sure may be configurable and left to auctioneer to decide.
Yeah that could be an option at the discretion of the seller. If I was selling a house I would want 144 blocks (24 hours).
I'm not so antagonistic towards sniping because it saves bidders much time and effort, and people tend to like it. You leave your maximum bid and system is responsible to apply it but not disclose it to others, and off you go just checking latter if you won or not. It's a feature actually IMHO.
Bidders love sniping because it allows them to win at lower prices which is not good for sellers. There could just be many options for the seller to choose from since every auction will have different needs depending on what's being sold.