What is visually appealing?

By now most of you would have read about Steve Job's biography by Walter Isaacson. I was intrigued by the incident when Steve pushes to have rounded rectangle. Now the question is how come he was able to observe that there were rounded rectangles everywhere! I look around now and see traffic signs with rounded corners but none beyond! Hmmm no wonder he really dented the future! Check out http://www.uiandus.com/blog/2009/7/26/realizations-of-rounded-rectangles.html
and
http://folklore.org/StoryView.py?project=Macintosh&story=Round_Rects_Are_Everywhere.txt