@Grant
allowing any idiot to write a review would result in the reviews being less than worthless, with the noise drowning out the signal
Given the sparsity of reviews, there is not much to drown out in the first place.
As to being worthless? Given that a reviewer (generally) has to explain the reasons for their score, there could be some comedic value to some of the reviews. The reviewer may not see that, but for the rest of us, there is a dark amusement to a review rating a story really low for technical ability, in a review riddled with spelling errors and crimes against punctuation. A bit akin to a TV interview with a rabid supporter for (insert political candidate of your choice here).
Then again, that just may be me...