Currently, 3 (#RGB) 6 (#RRGGBB), and 8 (#RRGGBBAA) character hex colors are allowed. Why not also 4 (#RGBA)?

The major use-case for me is that I like choosing colors from the smaller 3-character palette with only 4096 colors. In order to add an alpha channel, I have to rewrite these as 6-character colors and then add the alpha. I took a quick look through the code and it seems like this should be an easy change.