There should be an option to create color legends for any category and any parameter that would normally work with filters. Sometimes it would be create to color items based on their value but wouldn't be practical to create 50 filters to accomplish this. What if instead you could create a color filter for security, data, and communications devices that looked at the leading characters of a shared parameter to color them as a check looking at server zones.
The current functionality of color legends is extremely limited and is only accepted because it is all we ever had. Imagine if Autodesk said they were removing the filter functionality for all categories except these 5 categories. That knee-capped system would be the equivalent to what we currently have for color legends.