My thoughts regarding WFG reviews can be boiled down to one sentence: reviews are cultural work.
So, to go back to the original statement, reviews are things that take time and effort, which in some way relate to a way of doing things.
Short-term impact is easy and obvious. The review brings attention to the reviewed work, while also (hopefully) making people think. In the long-term it does something even more important, providing a very small piece of the jigsaw puzzle map that is Web Fiction Culture.