It's not a money thing. It's a principle thing. They're making a stand on principle that they don't license OS X to other companies because it makes other companies look better.
They don't want Dell leaching off Apple's marketing, especially in since Dell could use that to sell Windows tablets and Android phones to people they sell computers to. They want to make Dell associated with low quality hardware running crappy Windows. Allowing Dell (or any other company) to make machines running OS X makes that more... complicated. If Apple is willing to put their name behind a Dell box running OS X, well that's just one degree of separation past Apple putting their name behind the exact same hardware running Windows. It puts them in a very awkward spot of trying to sell the iMac against bland PC boxes, while supplying the software for bland PC boxes.
No where did I say it makes monetary sense or that it would be a bad move like you seem to be assuming. I'm just saying it's what Apple does, and from what I've heard, there are absolutely no plans to change that.
You do have to admit the clones were partly killed because Jobs loves controlling Apple's image as well.