Similar to the system that was in play in LabMUD, I think that most aspects and descriptors of your character should be handled from a code perspective. Things like your hair color, hair length, hair style, eye color, skin pallor, etc.
These should be able to be changed through gameplay, opening the field for various professions and skills (i.e. hair stylist). Changes in your body weight and height should open the field for various sdesc and description options.
Will expand more on this, but if anyone who played LabMUD recalls the system feel free to expand, and if anyone feels against feel free to mention it here.
It should still allow for player expression by allowing some aspects to be freely-written, and allow you to establish certain marks such as birth marks, scars, etc.