So, what am I asking for, what are shadow cascades? The way shadows, from the sun, work in modern games are called "cascaded shadow maps". Think of the sun as a camera pointed towards the ground that's at the same angle as the sun. Anything this camera sees, the sun can see, and so its in sunlight. Anything the camera doesn't is obviously in shadow.

Now Skyrim only uses two cascades, for performance reasons. One closer, and so the shadows are sharper and higher res close to you, and one farther away, so shadows don't disappear too far away. Shadows disappearing? Take a look at this: http://static.skyrim.nexusmods.com/downloads/images/6161-1-1326563387.jpg . As you can see, those trees in the distance don't have any shadows! Now if Bethesda allowed PC players to get up to say, 4 shadow cascades, then at the cost of performance those distant trees (and any other objects) would also cast shadows!

Also, in a purely technical note, why aren't the cascaded shadow maps fitted to the view frustrum? They seem to be centered on the player, which is silly. Seriously, that's my only guess as to why a 4k shadow map with a low area is still so pixelated. Just make sure the shadow map is fitted to the players view frustrum and you'd receive a free visual upgrade!

I agree about that since the Skyrim had released.
Distant illumination, especially distant shadowing are very important for depth of scene.
But now, with ShadowDistance=8000, near-shadows are very low-resolution, especially at 80-90 FOV (16:9). At 60 they are better by on stage. But 8000 distance still not enough at most places to provide at least self-shadowing trees at a distance.

Distant rocks at Skyrim are really awesome. Its sad because of distant shadows.