Cennydd Bowles wrote an article about beauty in web design. I think it is worth reading.

Why focus on beauty? Why does it matter that other design fields lead the way?

Beauty makes things easier to use. Our brains literally work in a different way, becoming more flexible when using a thing of beauty. This is theĀ aesthetic-usability effect.

Beauty is also infectious. Because it makes us feel good, we naturally want to share it.

But I believe the most powerful aspect of beauty is that it can change our perspective on the world.

via Beauty in web design, part 1 : Cennydd Bowles on user experience.