The thing I liked most in the NeXT was the sparing use of color. It was part necessity, but also usability. What does the color of the window bar being blue communicate?
I am an enthusiast for Gnome’s less is more approach.
The original NeXTcube was 4-bit grayscale, but there was a graphics card available which supported 24-bit colour. The later NeXTstations supported 12-bit colours without any additional hardware.