Clearly the author didn't bother looking up any retired designers or engineers from the time, as the article is mostly speculation. There were lots of reasons

Clearly the author didn't bother looking up any retired designers or engineers from the time, as the article is mostly speculation. There were lots of reasons why beige-ish tones were used. The biggest one was that's what IBM used, so to fit into an office environment, everyone else all followed along. There were practical reasons too: - ABS yellows under uv exposure (sunlight). If you start out yellowish, the fading is much less noticeable. - Beige mid tones hide flow marks really well. It means you didn't have to paint the outer case to get a 'perfect' appearance. The same goes for the comparatively rough textures used back then.