I do get it. In theory you would think that a bigger screen with pixels further apart would be cheaper to produce than a small mobile screen with double the ppi.
I figured out this Dell screen is 235 ppi so pretty similar to Macbook and other 'retina' equivalent laptop displays.
And I was comparing the current 27" 2560x1440 Cinema Display to the 30" 2560x1600 Cinema Display. The ppi increased a bit, but it is essentially "pretty much the same resolution".
That's a little unfair, considering the current 27" display retails for less than a third of the 30" model.
The fact of the matter is that manufacturing large, high-resolution displays is expensive, and that's due to a number of factors: the limited market for high-end desktop displays, the 2-4x increase in subpixel failures as resolutions scale 2-4x, and Windows.
Now that 4k tech is figured out, and Windows is no longer a complete failure at scaling to high pixel densities, expect the market to increase and prices to fall accordingly.
I figured out this Dell screen is 235 ppi so pretty similar to Macbook and other 'retina' equivalent laptop displays.
And I was comparing the current 27" 2560x1440 Cinema Display to the 30" 2560x1600 Cinema Display. The ppi increased a bit, but it is essentially "pretty much the same resolution".