Silmarillion - Chapter 14 - Of Beleriand and Its Realms

[Galadriel55]

Originally Posted by Aiwendil

It has often been observed in connection with LotR that Tolkien describes the settings and natural scenery more vividly than the characters; it would seem that a related impulse is at work here. Most of the characters in the Silmarillion receive very little in the way of physical description, but Tolkien pointedly interrupts the flow of the story for a vivid description of Beleriand itself.

I think this is because we can tell more about a character by reading between the lines, or by his/her actions. After all, the appearance of the people is not that important compared to what's inside. Land, however, doesn't have actions to judge it by. The only way you can percieve land is with a physical description - which (in Tolkien's books) reflects the "character" of a place, the events that happened or going to happen there, the people that live there, and of course the plot.