Here's my two cents: If people want to freely browse, then they can join.  It takes all of sixty seconds.  Restricting viewing also helps keep the art thieves at bay, which is bad enough as it is.  With bandwidth a precious commodity here, can you imagine how bad it would be if they allowed open access to the entire Internet?

No thanks.  If people want the same benefits of Renderosity members, then they can become Renderosity members.  If they don't want to take the sixty seconds to join, but are willing to spend 10 minutes viewing various galleries, then they really aren't interested in art.

There are several web sites available for people to place art that have no viewing restrictions in place.  PBase and Flickr come to mind as some of the more popular.  Both have hundreds of thousands of users and the community at Flickr is absolutely enormous.

Just my humble opinion.