> It positively affects usability, just like the other qualities you described.

It does indeed. "Aesthetics" in the most accurate sense of the word, as opposed to orderliness or just "looking right", is about how it makes us feel. Some people seem particularly sensitive to it and say they can't use a site or application that feels wrong. I respect that nuanced choosyness. Indeed I'm sure there's a biological thing going on, as in the way we select berries to eat or choose partners to mate with. Hard to introspect parts of our brain say "that's okay" or "that's off, don't touch". Aesthetics is very real.

But (there's always a but :) ... it should never be put ahead of functionality. As I see it that's what makes "Design" design, and not Art. It's blending aesthetics and elegance within a practical value set. And very often that "requirements set" is given to us designers by another... a film director, a product manager, an information architect etc. They say - "Here's what it has to do, (functional requirement) now go design it (non-functional)".

And what I am saying is that, in Web Design at least, the designers have gotten the upper hand, and that's partly the fault of developers, system architects, or project managers for letting themselves get pushed around like that.