I totally get what you're saying.
I wrote to amazon several times regarding certain preorders that had decreased in price but with no reflection on the order price. This is what they had to say:
"I do understand that the price of this item has again reduced on our website but it has not been reflected on your order status. As per our policy it will not be reflected on your order status. However, I would like to inform you that whenever you pre-order a book, CD, video, DVD, video game or software item from Amazon, the price you pay will be the lowest price offered by Amazon.co.uk between the time you placed your order and the release date
We can not reduce the price on the order as it may possible that the item price will reduce further. For more information on Amazon's pricing policies, please visit our Help pages at:
http://www.amazon.co.uk/gp/help/cust...nodeId=1040614 "
There is some very weird logic in what they write. I'm sure that in the past they modified the price in line with the fluctuations. There was a couple of times after I wrote in that they changed the price on my order at my request, but since the above reply they've stopped doing it. Anyway, I've ended up checking my preorder prices regularly.