I don't think that Apple really cares about the iMac.... they are making a killing with all the Gadgets.
From a combination their quarterly results, so this might be off a bit:
For the 2009 fiscal year:
10.39 million computers sold
54.14 million iPods sold
20.75 million iPhones sold
It seems like the gadgets trounce their computer business, and in terms of numbers, this should be the case. But the computers are significantly more expensive than the gadgets. As for their revenue, sorry, I don't have access to their annual report. The above was all public from what Apple released.
Regardless, I seriously doubt Apple doesn't care about their iMac customers. They have to represent a fairly decent portion of Apple's revenue, or else the iMac would have ceased production awhile ago.
Rather, I personally believe it's damage control. Apple screwed up. Lack of quality assurance, greed, etc., something went wrong. The fact that they changed their return policies is proof enough of this. So I think they looked at the bottom line, and saw that sacrificing a few customers is more profitable in the short or long term than trying to fix the problems that arose.
There will always be the zealots who wear Apple shaded sunglasses and refuse to believe anything could possibly be wrong. There will be the people who grumble about this generation of iMacs, but will still use them because there's no realistic alternative for their needs. There will be the customers who lucked out and managed to not get a flawed machine (be it the first time or on a repair/exchance). There will be the people who use other Macs. There will be people who are upset, and requested a refund, but are positive about the future. All of these are Apple's future customers.
But I find it hard to believe, given on Apple's official forums, and other forums such as this one, that this generation of iMacs isn't seriously flawed. But how many of the customers who bought one do not fall into any of the above categories? And how much money does that translate into versus the amount of money needed to fix all the broken iMacs from customers (or at least satisfy them with an alternative) who do fall into the above categories?
I don't think anyone is honestly asking for a perfect monitor. For a machine the size of the 27" iMac with the internals it has, perfection isn't realistic. Heck, the EIZO ColorEdge CG243W costs about the same as the base 27" i7 iMac, and that's only a 24" monitor. But customers at least want acceptable working conditions. I understand that acceptable is subjective, but at least for me, what I'm looking for is a monitor that appears flawless with a quick glance. Most of us wouldn't purchase a car at full price if there was a huge dent on the hood (and the car wouldn't be sellable if the windshield was cracked), so why should it be different when purchasing a computer? After all, both of them are only aesthetic problems for the majority of customers.
unit. 
