I could not agree more. I am stunned this doesn't already exist. This is not exactly a highly advanced feature and should take a programmer two days to implement and another week of interface testing. PLease get this implemented.
What is really strange is that it seems to be hard-coded into the code, as there isn't even a parameter file, .ini-file or even some values in the RegDB (not that parameters should ever be put there, but God have I seen many stupid and wrong uses for RegDB). The first thing I looked for was the option to go to a .ini file to see if I could find a list of RGB or HEX color codes to adjust, but no such luck. (I may have looked the wrong places, but that would really have been such a nice feature).
BUT... IF you choose to implement this feature, at least ALSO make it possible to implement MORE than the limited number of colors that are available now. (I often like to vary the colors within a group of tracks, like making the main track one color and then the other tracks within the group slightly faded, but the same color to make it possible to see what color it is).
One last thing. If the background color of the track can be set limitlessly it might be a good idea to either automatically make the audio representation (in audio tracks) in a contrast color so it isn't always white, or you could make it a dual function option where you can adjust both background color and curve color adjustable. That way you also give people with many tracks and groups a lot of variation, so the same color could be used on several tracks but with a different color for the audio representation.
This is really something I need a lot.
