This old Sparcstation I managed to get for free years ago would display everything in "light mode" by default. If you would boot Linux or NetBSD to the console it would be a white background with black text.
Image: http://www.computinghistory.org.uk/userdata/images/large/21/...
I don't know how common this was, or if it's something that was unique to these sparcstations.
I think it's because computers like the Mac were geared around desktop publishing.
There's no absolute reason why the evolution happened that way that I can say. It was all more or less arbitrary design decisions.