Not to argue with you, because I've always felt it was that way as well, but after attending a recent coference with some IP lawyers I was shocked to find that (at least according to them) purchasing Movies/Music etc. is NOT actually purchasing the "right" to that content... but that the laws are more like that of purchasing the physical media as an item. It got me thinking about it...
I believe the scenario you described only falls under Computer software where the disc is used for installation and you have licenses and license keys which you can purchase without actually receiving additional media. Also with computer software the physical media is typically useless without a license key, and the software companies will more often then not send out as many new discs as you like as long as you own a license.
IANAL but the way I've come to interpret it is that CDs, DVDs, Video Games etc. since they do not have a License Agreement that the consumer signs, or even virtually agrees to, that consumers are actually buying the physical media. This is further re-enforced by the fact that most companies will refuse to replace damaged discs or allow you to obtain the same software in a different format since you already own the license.
Legally the whole situation is rather nebulous.
It seems to me that the RIAA, MPAA, and to a less extent the ESA want to treat it like a license when it works to their benefit, and at the same time they want to treat it like a physical product when THAT works to their benefit. Not to mention that you can't make legally binding contracts with people under the age of 18. If purchasing CDs, DVDs, or console games are actually purchasing licenses to use the content, then it would also require the consent of a legal parent or guardian for all purchases to be legal, most EULAs on computers have that text in them regardless as to whether or not people follow them.
Using the analogy of a car... if you buy a Chevy car as a physical product from GM you can take it home and tear it apart, attempt to machine duplicate parts and build your own car, better yet you could use both of them to drive around your land and do whatever you want with it. But if the car breaks, it's your own damn fault because you bought the car it's your own responsibility.
if you buy a license or "right" to drive a Chevy car from GM they can setup boundaries that say you can't duplicate that car, and you can't drive it around your own property unless certain conditions are met, etc. But if the car stops working GM should replace the car, because you would still own the right to drive one. If it broken under terms of acceptable use GM should replace it free of charge, if it broke because of your own fault, you should be able to pay GM for the damages to the car but still get it replaced.
Purchased disc media works like neither of these situations.
I'm not entirely sure there's really a "system" to change but looking at the way it's treated it certainly leans more towards the purchase of a physical item as opposed to a license.
-if the disc breaks you will not receive a replacement and must purchase it again
-there is no contract signed or agreed to
-minors are able to purchase them
-you can buy / sell /rent used discs (AFAIK none of that is legal with licensed content)
About the only thing that DOESN'T make sense is that they want to control how you can use the media once it has been purchased. This does not fall in line with the legalities of a purchased item, but instead that of a licensed one.
So again, I believe there is no clear cut laws on where these things fit, and it seems to me that Association-X wants to treat it like one type of purchase or another depending on what fits their legal needs at the time.