On the other hand, businesses generally buy PCs because they're far cheaper, but the market for MP3 players in a business context is basically non-existent, whereas it's potentially huge for the tablet market, so that's another mark against Apple.
It'll be interesting to see how it all turns out.
As highlighted in the iPad launch, Apple introduced the modern laptop with the first ever PowerBook. The laptop market is now definitely commoditized but that doesn't stop Apple from making a lot of money selling fewer highly profitable laptops.
They have something under 10% of the total laptop market but 90% or more of the segment > $1,000 per computer.
Actually, they'd probably wind up selling more of their kit by doing this!
Since technology advances faster than consumer demand, the differentiating factor for purchases changes over time. First it's possibility, then power/flexibility, then price, then convenience/usability. iPods and mp3 players got cheap enough that the usability of th iPod/iTunes Music Store became the deciding factor and there was no demand for undercutting it on price.
Also, the music use case is so well defined that there wasn't much room to compete on flexibility. PCs have miles and miles of flexibility, but by defining the role of the iPad as music, movies, books, and games (basically media consumption), it might be staking out a territory where it can outperform everyone rather than compete with commodity devices.