Wait, so you'd have to memorize which color the enemy is and which color your teammates are just so you know if these colored units are friendly? In my opinion this isn't a good idea. If you see a scarab approach you base, and it isn't you teammates, then all your units you had stationed outside the enemy's base to prevent from expanding will come back to defend your base only to realize the black scarab(which would look totally cool I will admit that) was your teammates the whole time. I like the cool/warm color team or red/blue teams. Only having 6 colors in the game and the three that go together as a team being right next to each other in the color wheel is great because it's easy to differentiate what's friendly and what isn't. If we had 20 colors like you mentioned it'd be a nightmare to remember who's team your on. Sure you could press the back button but that takes precious time and time is very important in this game.

In conclusion I think having customizability to units is a cool idea. Like making the blister back and locust look different. But adding new colors is not a step in the right direction. It's 3 leaps backwards