To be annoying, and not to disagree with your comment in any real way at all, I’d argue it’s the engineers who are being irrational for choosing to ignore or not make the effort to understand human nature. I’m sure there are plenty of studies in psychology, social psychology, or anthropology explaining the rational basis behind why fashion/marketing has such a strong impact on human behavior. I’d also bet that the advertising industry is well aware of these studies ;).
It drives engineers batty, because it's often irrational.
Just because something is irrational doesn't mean it doesn't have a huge impact on something like adoption.
If we didn't care how things looked, we might all be wearing google glass.