The Dell E248 has a TN display. In other words, the cheapest there is. There is no comparison with the ACD. It's misinformed to make any comparison between a TN and a S-IPS.
The NEC 2470 uses a S-PVA display, and thus is not as good for pro color work as a S-IPS display. And it is for this reason that NEC also has in their range the NEC LCD2490WUXi which does have a S-IPS display and costs $1100.
A wider display is not better if it has the same number of pixels. It just has a bigger pixel pitch. So it depends on your preference.
You want Apple to make a cheaper display, but then they'd have to use the cheaper PVA panel. Then you should just buy the NEC Multisync 2470. The ACD is a pro level panel, and hence it has a S-IPS panel. Similar, pro panels such as the NEC also have S-IPS displays and are considerably more expensive.
You want Apple to reduce the price of the ACD and use cheaper materials. It's like asking BMW to make a Ford. The target consumer of the ACD certainly doesn't want that to happen and if they were to put a PVA panel in there, they would lose a lot of sales from the professionals who require the best panels.
Very good points all around my friend. I tried to make a case but you have definitely proved the case in Apple's favor.
The hardest thing to find on the web for me is whether or not a display has a S-IPS panel or S-PVA panel.
Where were you when the Dell lovers were bashing every other display out there? Off to get the 30" ACD then.