My theory is, sealed bids work best for retailers who just go in and bid a high amount on almost ALL of the MVs. Most individual pockets won't reach so deep. So we cannot see what the competition is, the price is, and cannot bid it up.
There are many advantages to bidding up a price. One is, if it is long distance, you cannot preview, you get a feel for what is the best few of the lot, based on early and final prices.
It gives you more confidence to bid up a price where the price is already high, often, but not always, previewed by someone who knows the "best of lot".
And if not fully knowledgeable of the item, and a first time buyer, the open bidding process gives you a good feel for what the item is worth in the end, as you see the final price. You can chalk it up to experience.
You get no experience, no knowledge, no confidence in the sealed bidding process due to the lack of information provided during and after the auction.
I'm all for "true transparancy" in the bidding and sales of surplus items.