When you have a complex workflow and you need to identify what happens to a specific field throughout a LONG workflow, it would be great to have the paths, connections, etc highlighted.
If the field is modified in a tool (formula for instance), the tool gets highlighted in orange. If it just passes through a tool, it is highlighted in green and a tool where it gets dropped is colored red.
This will help in identifying which tools modify a field of interest as well as identify tools which "deselect" a field and cause it drop out. I spend a lot of time tweaking workflows developed by other analysts, so this will greatly speed up troubleshooting and assessment time.