It's only a business necessity if you think your customers are thieves. See Baen's Free Library for an example of a company that doesn't, and is quite successful nonetheless.
They're totally different business models, and if I had to guess, I'd say the iTunes Music Store has been a tad more profitable. Oh, and by the way, you can download about a zillion free podcasts from iTunes, that include business, media, science and technology, comedy, and yes, free music.
I'm a big fan of Baen's library and webscriptions.
But the iTunes DRM is a business necessity because that's what the suppliers demand for the right to sell the music. Apple is a retailer of the music, not a producer, and thus Apple does not dictate the way it sells music, television shows, etc.
It isn't that hard to understand. The DRM is a business necessity. It is also obvious that it is a necessity imposed by the producers of the music.
Do I dislike the DRM? Sure, but honestly - it makes no difference to me. I don't share the music I buy with just anybody, and the terms of use are very simple and fair. Five machines, unlimited burns, unlimited plays, and I don't have to worry about my ownership of the tracks I buy expiring.
Besides, a fair enough DRM is not onerous. Thanks to the DRM and iTMS, I can buy the tracks I like for 99 cents. I don't have to pay $15-20 for an album at a music store just to get a single song. The DRM has saved me money, and iTMS has saved me time and gas.
I don't know what all the bitching about iTunes DRM is about anyhow. Between Audible and iTunes, I get a lot of use out of iTunes, and my iPod. Oh, yeah - that's right. Some people are upset because they have their own MP3 player but they want to buy cheaper music from iTMS and easily sync their third party MP3 player with iTunes. Not my problem. If people want to use iTunes or an iPod, but not together - tough. I want Microsoft Exchange Server to run a Macintosh, and the Exchange functionality enabled on all of Microsoft's applications for the Mac. Tough for me.