Seeing what others are bidding wouldn't do you any good anyway. I have some good info that the number 1 for my ideal search term, pays less then a thrid of what I have ha dto pay to get there, so seeing exactly what they pay might be interesting in a purely academic way, but it wouldn't help me increase my sales any.
it is not just seing, you can then bid 1 cent below the top guy to be #2 or 1 cent above him to be #1. It helps to see the bids.
This was probably true back in the day, but now the algorithms are far more sophisticated and it doesn't work like this anymore. Many factors are taken into account when the engines decide on which ad ranks where. Look at Google for instance….they are calculating QS, which is a big factor in ranking, at the time of the query.