1. The content they want.
2. Quality (i.e. resolution, bitrate, etc.)
3. Reliability (it actually plays)
4. Low annoyance (no ads, warnings, etc.)
5. Safety (guaranteed freedom from malware, etc.)
The movie and music industries haven't done a perfect job of delivering #1-4. Region coding means the content users want is frequently only available through pirate channels. Lower quality releases (DVD vs Bluray) are also often all that is available in some regions. Bluray is not reliable if users don't keep their hardware/software up to date. Nearly all DVD's and bluray discs on the market are utterly infested with annoying advertisements and warning screens.
#5 was the one thing that legally purchased media had an undeniable edge in over pirated media. If users lose trust in the safety of legally purchased media they will be driven to piracy in unprecedented numbers.
It is tempting to give RIAA and MPAA the rope to hang themselves with, sit back, and laugh. However, let's not forget that every piece of code they write and every root-kit they successfully deploy will soon be taken advantage of by black-hats, quite probably in ways that will cause damage to systems completely unrelated to media playback of any sort. The only way I can see to let the MPAA/RIAA proceed is to require them to post a significant bond (in the billions) to pay for damages their rootkits will cause. Managing how damages are going to be awarded is going to be a legal nightmare though, since this will not affect only U.S. systems and citizens. If the U.S. permits this, I sincerely hope other nations hold the U.S. government responsible for damages, so the U.S. had better make sure Hollywood is ready to foot the bill.