Allow For Further Customization
Further customization beyond the two choices for page theme and 7 choices for color theme. If your brand does not match those colors that you will not be able to "seamlessly" integrate the system with your site. The is really a key feature in my opinion. Perhaps it would be simple enough to put a color picker in there for each of those two elements if you are not up for a full blown brand integration feature.
Jenn Cash commented
Most important to me is a color palette with many more than 7 colors. Color coding projects is very helpful but I need closer to 15 colors to make it really work. Agree, a color picker would work. Or the existing 7 colors could be used in 2 or 3 tints.