4:3 laptops become too bulky and too deep. Don't get me wrong, I loved my ancient 1600x1200 Lenovo T60p, but it was a beast to carry around and required tons of lap/table space. 3:2 fits significantly better in a bag/backpack and significantly better on a desk or airline seat back. 3:2 gives significantly more visible space than 16:9 or 16:10 while still being trivial to move my fingers up and tap on something on the screen (unlike 4:3).

Furthermore, 3:2 screens are available at proper useful screen densities. 1080p is too coarse even at 13" (and unusable at 15") while 4k is so dense as to be a waste at anything below 17". 1440p is quite rare. 3:2 screens, on the other hand, come in at usable sizes like 2256x1504 (Framework), 2496x1664 (Surface Laptop 3 15"), and so on - enough DPI to give you beautiful crisp fonts without requiring you to keep shoveling lumps of coal at your GPU to drive your desktop.