In a lot of people's cases, you're also paying for the look of the brand too. It's funny, because as I get older I can tell that my priorities are changing.
Back in college, I'd spend a couple grand on a nice home theater system, just to spend twenty bucks at Home Depot to buy cinder blocks and wood for a makeshift entertainment unit to house it in. These days I'll spend a couple grand on a nice entertainment unit, and then think about the electronics to go in it.
Anyway, although a black LCD looks better on my current desk than an Apple display would, you better believe that I'd shell out a few hundred extra for the Apple if I thought the reverse were true.