1) False advertising. Steve is getting a big group hug from the blogosphere for eliminating DRM, when it’s simply untrue.
2) Privacy. Nothing about playing an MP3 should require releasing personal information. What if I had to sign my name on CDs when I bought them? Totally lame.
3) False lawsuits. People are going to crack this DRM (just like every other DRM has been cracked). A simple, rudimentary crack would involve inserting a fake AppleID, or someone else’s AppleID. When those cracked files hit the net, the RIAA & Co. will sue the owner of the AppleID in the file. I’ll bet wildly large sums of money that they will finger the wrong culprit on many occasions due to cracked DRM. And, courts will never hear a word about it because the VAST majority of these shit lawsuits are settled for the $5,000 ransom notes included with the subpoena.
4) Secrecy. If a watchmaker is going to engrave my name in a watch before he sells it to me, then he should ask me first. If it’s a necessary condition for sale, he should tell me so. Same goes for Apple. Apple should be publicly stating during the checkout process that this engraving is occurring. I tried it buying the “free song of the week”today, and there is no disclosure to engraving in the checkout process. “Shhhhh… spying on users doesn’t work if you tell them you’re doing so!” Security through obscurity is weak and deserves to be exposed.

I take from your comment you either A) don’t care and genuinely wonder why I do or B) assume I am upset because I want to pirate these songs. If “A” then I’d be happy to debate these points and keep the discussion going. If “B” then I doubt these points will have any effect on your opinion.