The Bouba and Kiki Effect in Music

Why is it that Axel F is such a spiky, star-shaped song, while lush orchestral music with lots of strings is billowing and bulging and round, like a fat white storm cloud on a humid summer's day?




As a stark contrast this is a YouTube music clip of Fantasia on a theme of Thomas Tallis by Vaughan Williams. Note the choice of image for the cover art!
http://www.youtube.com/watch?v=r7qJFgOlbXc