Well, that's not technically true. If the courts find in their favour -- forcing ISPs to submit to their subpoenas for names/addresses -- they can sue you, and take all your money (due to the strange way they calculate damages).

That, of course, depends on a) you residing in the US, and b) them actually picking you out of the pool of millions, which is statistically unlikely.

As for who cares? Well, probably not the people that don't think there's anything ethically wrong with downloading music. However, if you're worried about your anonimity when all you're doing is breaking copyright laws and trading music, then you don't fall into that first group of people, and are doing something you know to be ethically wrong and illegal -- you probably care.

But that's just my take on it.