The list of user reports is certainly interesting in that you can see how many times someone has been reported, but having who reported people could cause some more problems for people down the line. If someone is being disrespectful, harassing people, etc, then the person being reported can easily see who reported them and can just target those people more. They can also then click on those peoples names in the list and go to their steam profile and follow them through that.
Some people may be turned away from reporting because they don't want that risk, and it would be a bit safer for people to report if who reported them isn't made public (but can still be kept for admins and what not)