I think that it would be too much trouble.
1. If we get to change it freely, moderating what we write there would be too hard for the staff. because lets face it, some do not respect the rules, or consider that this is still a forum for underaged people as well.
2. If we get the option to buy/earn it, and if it would be up to a staff-member to write it there, it would bring even more work for them.
3. Those who has "formerly *name here*" could not get it changed anyway, since I think that needs to be there to prevent misunderstandings on ones identity etc.
4. Even though it is an option to express ourselves and make us different from others, it is unnecessary. We can already modify our profiles, sigs etc. in order to express ourselves.
5. Aarin, Dai or idk who, obviously put a lot of trouble coming up with our current ranks. If everyone would get the chance to just change them however they please, the current ranks would become totally pointless.
I have nothing against the special ranks really, just that this forum is huge. Even if there would be restrictions on who gets the option to change it, the group would most likely not be small enough, and even then the rest of us without that option would get pissy.
//wasn't there an option to buy this before? Like, loong time ago? If there was, and there isn't anymore, it's pretty clear what the admins answer is anyway.