I love having dual exhaust it just looks right.There is other reasoning besides cosmetics behind dual exhausts.
Dual exhausts having two mufflers permit higher gas flow while at the same time have lower exhaust sound level.
Symmetry is, obviously, the "cosmetic" component of the design. Humans... and living things in general are symmetrical things where symmetry is a defining component of beauty. It only follows we define our cars similarly.
Also consider the fact that the entire rest of a car is symmetrical. A single exhaust, therefore, stands out as a major "wart" in an otherwise harmonious visual package. There is more than one reason the grapefruit-shooting fart can is ugly besides its sound.
Yes it may be for aesthetics but it would look off if it only had one tip (at least on the SH)
My foz with dual 4" tips
DSC_0852 by Puzzles Photography, on Flickr
DSC_1057 by Puzzles Photography, on Flickr