I am old enough to remember when Brown and Ivory were pretty much all they had. I assumed it was just a manufacturing thing and people were used to the idea that this was all there was. I agree the brown plastic evolved from the original bakelite. I think the next color to come along was red, then orange but they were both industrial use items and very expensive. You were not going to see than at the hardware store or home store.
These days you can get about a dozen colors.
