Smart cards can be made nearly impossible to hack--see DirecTV, et al. And with the DMCA, hacking it would be illegal, NO MATTER what the intent.
Also, smart cards can be married to specific players-- conceivably you would need to buy the White Album for the home player as well as the car player. Heck, the access method is programmable, there could be all types of control mechanisms implemented. And since we have this smart card reader interface, maybe instead of buying media, it would instead be distributed freely (or very cheaply)-- but you'd have to pay to listen. Just insert your Music Choice (tm) card and a number of credits will be deducted. Yippie. (Damnit, I need to patent this. :-)
I've always liked the idea of credit card-size media, but I'm afraid the next generation media is going to be down right draconian.