I think what people are concerned about is let's say you bid $300 with a max of $500. Someone else comes along and bids $400, but is immediately outbid by your max of $500, let's say it shows $425 (assume a $25 increment). The auction ends and the person who started bidding at $300 looks at the bidding history and all they see is another bid for $425 by themselves. They don't see any other bids, what that person is wondering is "who" forced my bid to go higher, was there even a valid attempt at bidding against them or was it some shill or worse still a moderator or administrator of the site.
In essence the bid history as it stands now is simply the "successful" bid history but not the "complete" bid history. I think an administrator should be able to see the "complete" bid history to check to see if any monkey business is going on (shills etc.) or to alleviate any fears of the high bidder who looks at the history and sees what looks like them bidding against themselves.
Hope that makes sense.