What's the saying about fools and money and parting?
There's some weird (i.e. wrong) logic on this thread.
First someone picks $1,000 out of the air. Then it's $10,000. Both figures are wrong.
A really high quality 27" monitor is perhaps $2,000.
Now is that worth it? Well it depends what you want to do with it. Just surfing the web? Maybe not, but it's a personal choice and if you hate clouding, blacklight bleed and other horrors, perhaps it is. I bought an Eizo partly for these reasons.
But the main reason is colour accuracy. If you need to produce photographs or art work and you want the finished output to look exactly as it did when you created it or worked on it, you need a colour-accurate monitor, and ideally with a wide gamut so you can actually see on screen the full range of colour you might ultimately send to the printer.
You will need to calibrate the screen, of course. But you also need one that has consistency of colour across the screen, from side to side and top to bottom. It's not just a case of getting a crap screen, calibrating it, and then it becomes a brilliant screen. Ideally you want the calibration done in hardware (not software), so are you correcting how the screen is performing at its base level.
All of the above costs money, hence the $2,000 price tag. First, they only use the best panels - the ones with no dead pixels and the best uniformity. And they add to this sophisticated electronics and calibration features.
Personally I do NOT think it would have been sensible for Apple to build all this into iMacs. It would probably have increased the base price by maybe $300, for features most people don't need. And if they offered it as an option, it would be like admitting that the standard screen is a bit crap really.
So I think they made the right choice. But that does not mean the iMac screen is superb - it isn't.