I tried to figure out why, and I think it's a really dumb reason: like this article says, if you don't really know what you're doing with design, you want a spectrum of light-to-dark colors to choose from. Light green -> normal green -> dark green.
For some weird reason, we call light red "pink". And dark orange/yellow is "brown". If you pick one of those as your main color, it becomes much harder to just use lighter or darker shades without it becoming something else entirely. Great designers can make pink or brown work, but if you're a programmer who's just trying to find a "good enough" color scheme, it's way easier to go with green or blue.
I don't really have a good reason why we all think of pink as a different color from red, but we do.