I would encourage you to read this article over at A List Apart. In Defense of Eye Candy by Stephen P. Anderson

He makes and illustrates a lot of great points about the role of beauty and attractiveness in the effectiveness of interfaces.

What I really like about the article is that is supports the need for "complete collaboration" between the UXer and the Graphic Designer. Neither one exclusively holds the power or skills to create the most successful experience. The work is so intricately joined. I'm starting to think you can't do your best work unless you are actually sitting next to eachother working each step of the way together.

I have a little dream of finding the perfect design partner, someone to develope the ultimate collaborative relationship with and create mind bending experiences together (maybe even take over the world). What if no one hired a single designer, you had to come with your design twin? Could be fun.

A few good passages from the article:

"As user experience professionals, we must consider every stimulus that might influence interactions"

"In other words, aesthetics is not just about the artistic merit of web buttons or other visual effects, but about how people respond to these elements. Our question becomes: how do aesthetic design choices influence understanding and emotions, and how do understanding and emotions influence behavior?"

"Basically, when we are relaxed, our brains are more flexible and more likely to find workarounds to difficult problems. In contrast, when we are frustrated and tense, our brains get a sort of tunnel vision where we only see the problem in front of us."

Head on over and have a read.