I think they should implement a custom shader option from Eva Levante. For X amount of motes or strange coins you can chose your own colors for each of the three parts of the shader. Normal colors would cost lower than patterns or neon/glowing colors. They could easily implement this in a similar fashion that you chose different shades and skin colors for your original character build.
For example, all of the colors that are available for rare/blue shaders could be 5 motes/coin each while adding any kind of pattern (camouflage for instance) could be an addition 5 motes/coin. If you wanted a neon or glowing color, like the way Glowhoo is, that would be another 10 motes/coin. So, if you chose to have a base color with a pattern for the outside square of your shader, a neon color as the outer circle, and a regular color as the main circle, that might cost you 25 motes/coin.
They could easily have a preview of the shader you chose before purchase in the same way they do now. That way you can make changes or tweak what you want your shader to look like.
This system would easily add more variety to the way each Guardian looks even if two people are running the exact same gear or build.
What are your thoughts on my idea? Feel free to sound off below.