Earlier quoted context omitted.
The UI found in WorkBench 1.x was designed to be the way it was so that owners could plug their Amigas into television sets of the day and still be able to make out something without requiring a pristine purpose-built CRT monitor.
This is actually wrong because most of the A1000s were bundled with an RGB monitor and an optional composite out. The system wouldn't be really connected to a shitty TV until the budget models were released well after OS 1.X color scheme was established. As far as I can tell the blue/orange scheme was instead aimed at monochromatic monitors .
Ah. I stand corrected then.