User blog comment:Reversinator/Skyrim: Characters category/@comment-3186827-20120623221812

The reason Riverwood has it's own category is it's quite large for a village and its reletively important as it's part of the main quest. The only reason Rorikstead, Karthwasten, Ivarstead and Shor's Stone don't have their own characters by location category is because they simply have not been created. In addition it's debatable if it's even useful as Shors Stone, for example, has only 4 characters.

Characters by Hold was discussed a long time ago and it was decided it's was far less useful than breaking it down by city. Skyrim: Locations by Hold exists because locations are not treated in the same way as characters, so breaking them down by hold makes more sense. But we also have categories like "Skyrim: Whiterun Locations" for added granularity anyway.