Why wouldn't they be? Look at the price difference between a
1080P 27 inch screen and a
2560x1440 27 inch screen....
I think lack of predator-like competition is one answer. Right now HP, Dell and Apple can sell people 27 or 30 inch screens with 2560x1600/1440 resolution for $1000-1,300 and people still buy them. Why would those companies lower prices or sell us a 30 inch screen with 2x as many pixels? They haven't dropped prices in 4-5 years. As long as that small group of consumers are willing to spend $1000-1300 on a 30 inch screen, companies have no incentive to lower prices or innovate. I somehow doubt that it costs 3x more to manufacture a 1440P 27 inch monitor than a 1080P 27 inch monitor.
Samsung S3 will supposedly have a
4.8 inch 1920x1080P display this year. The next 10 inch IPad 3 will most likely have 2048x1536 display, starting next week. If smartphones and tablet screens are increasing their PPI and screen sizes, that means over time larger screens with higher resolution are becoming cheaper to manufacture. We should see the same trend for all screen sizes and all screen resolutions over time.
There is so much competition and consumer demand for higher quality screens in the tablet and smartphone market that companies cannot afford to stand still. It's probably a catch-22. The number of people who want a 30 inch 2560x1600 or higher resolution monitor for $1,000-1300 is too small to justify investing heavily into R&D to make 30 inch screens with 2x the resolution. But because 30 inch screens cost so much, so few people buy them in the first place, creating a lack of demand given the price. What you have then is complete stagnation in that segment in the last 5 years.
Still, even I find it hard to believe in the cost argument. Pretty much all sizes of 32-80 inch plasma and LEDs have come down in price over the years. 30 inch 2560x1600 monitors? Have barely moved. There is no way that it costs the same to manufacture a 30 inch 2560x1600 screen as it did in 2006. Why are they still $1,000-1,300? Like I said, consumers are still paying, and those companies found the 'optimal' equilibrium of probably making huge profits selling to a small % of the market.
Considering companies like Sony, Samsung and Panasonic continue to lose millions of dollars on their TV sales, the highly competitive, thin profit margin TV screen industry's performance gives an even higher incentive for companies to try and maintain what are surely few highly profitable product lines. They were able to create this allusion that 27 and 30 inch screens are "special" and thus warrant high prices/high profit margins (such as 30 inch 2560x1600 screens at $1000+). It's marketing 101. And consumers have accepted it since the alternative to a $1000-1300 30 inch Dell 2560x1600 screen is a $1000-1300 HP screen....with a similar panel to Dell's and the same ugly plastic casing.