I definitely consider the appearance when I lay out a PCB. I will see it, and other engineers will see it, and I know that when I look inside a product, I can usually tell something about the engineering that went into it by looking at the PCB layout.

There is also the fact that layouts that look nice tend to work well too. A lot of it is likely the attention to detail that went into the design, but there are other aspects. Similarly, a great many of the best looking airplanes fly the best too.