This is BAd thinking.
If sony would like to add this feature into there systems, "which they already have" Creating an account on a japanese account, you have the option to change your PSNID as a secondary format. Your primary PSN will be the original PSNID, but the Secondary PSNID will display to others on your friends list.
If they added the feature to change your primary PSNID, they will not do this for free. They would install a curency system, so to change your name, you would have to pay $5 etc.. Its the same as xbox!
It is a good system, but it is not needed.