I will start with the basic. I have 5 nether stars, I need to sell them now, and I know the base price is 500 per. I could then go 5 nether stars starting at free! Rsv:2500. So, if bidding only goes to 2400, if I wanted I could take that offer, but I still retain the right to deny it seems how it didn't meet the reserve price. Now, I understand this could be abused. By throwing on insane reserves just encase your item doesn't get what you. I feel that this is something that might be moderated somewhat, or screen pictures could be taken if it happens consistently and that play could be reported by the players. I feel that this addition to the auction system, could increase the overall sell of items as a whole, as people would feel safer about posting items and such. As mentioned above, there is the area where is can be abused, but, I would hope that isn't the case.
I see this ending up with a bunch of auctions with no actual winners. Of course, I could be wrong, but I don't imagine this doing any good. The auction we have right now is good enough and you can just start it at $x amount.
This would actually clear out nearly all repeat auctions of the same item by the same people I believe. Therefore, cutting down on the already low population of auctions. Already, unless someone starts the auction at free, I see nearly the same amount of auctions getting no bids, as I do whom start low. But thanks for your input, Dumdum. 8^)