how about instead of complaining about the posibility or lack of colours, I've got a solution:
the new iphone has a flat back therefore it will be stupidly easy for 'screen protector esque' sheets to be produced in a rainbow of colours for you to change the colour of the phone, the same can be done for the front if you so want, also a clear one for the back so *IF* it scratches easily then it can be protected and hopefully stop people using ugly fat cases on the phone,
and because the back is flat it will be easy to apply and change depending on your mood