Why doesn't the iPhone 5 have a colored back and strap?

Okay the new iPod touch has a colored back that comes in black, white, pink, red, yellow, and baby blue. Along with straps that match the back.

I'm not going to get the iPhone 5 but, I'm just curious because it seems as if they would get more consumers if it had a colored back like the touch. Could it be to market towards kids because not much kids got the iPod touch 4 or is it to much money to produce a phone that comes out in 8 colors?

(I'm getting the new iPod touch)

No one cares about the color