At just a handful of reviews a month, deleting reviews might alienate some of the only reviewers Unsung's got. It's not like they aren't coupling the odd Pet Shop Boy review with something tasty like Franco Battiato and Mark Fry (by ON-U-Sound and flashbackcaruso respectively, who seem to be the people you're referring to).
The list of albums reviewed over the last couple of years reads pretty interesting to me. I wasn't one of this site's early pilgrims though, so I don't have a reference point.