I think they've done the math on this one. They very heavily segment the market and most Apple users own several Apple devices. They fundamentally don't believe in the idea of one device being all things. This is also why their laptops don't have touchscreens.
I also don't think you can't bring all this to a device like an iPad and not alienate part of the existing market.
I also don't think you can't bring all this to a device like an iPad and not alienate part of the existing market.