The important term for the importance of inches I think you are referring to is DPI or Dots per Inch.
Here is the math for a normal 16:9 27 inch monitor.
27" x Square root of (9 squared /divided by (9 squared + 16 squared)) = The vertical size of a 27" monitor is 13.2"
Or about half (27 x 0.49) = 13.2
Now calculate 1440p / 13.2" = 108 Dots per Inch. Which is pretty good.
I once used a 32" 1080p TV as a monitor. That was 69 DPI. I would never want any lower than that.
Apple 'Retina' displays are 220 DPI. Above 200 DPI and it's really hard to see any pixels.