Not sure what you mean in first sentence? I have found the node lines to be useful for navigation, and the edge lines (drawn darker and in front) create "edge w

Not sure what you mean in first sentence? I have found the node lines to be useful for navigation, and the edge lines (drawn darker and in front) create "edge wedges" that make nodes with similar neighborhoods stand out. Without lines, you end up with just an incidence (as opposed to an adjacency) matrix.