ASCAP needs distribution. Just like the labels agreed to many things they didn't like to get on iTMS (DRM-free distribution, selling singles instead of albums, fixed pricing, etc) they will see that Apple dominates the digital music distribution industry and even they are not stupid enough to give up a large, established revenue stream chasing a new one which they have never received before (how many stores that have kiosks to allow you to preview CDs are paying performance fees?)
Early iterations of services like the legit Napster, PressPlay, Rhapsody, etc showed what the industry wants from digital music and also showed that the vast majority of customers will opt for piracy or nothing ahead of that option. The people in charge of RIAA and ASCAP are obviously out of touch with reality but they are, if anything, bean counters and will almost certainly be able to look at the numbers and see that they stand to lose far more than they stand to gain by making a stand on this nonsense. I think that if Apple simply says no this new demand will go away. If popular artists start disappearing from iTunes it is pretty much certain that a significant number of people who would have purchased them will torrent them instead and that is the last thing the labels want.
"Following a torrent of customer complaints" Is that torrent available on the Pirate Bay? I have been unable to find it anywhere.
Probably, everything else seems to be
Why only people who link to it?
A true student of the RIAA would just start suing people at random and offering them the chance to "settle" for less then the cost of defending themselves at trial.
Trying to be happy is like trying to build a machine for which the only specification is that it should run noiselessly.