For RP purposes. At least for me. Different hairstyles/tattoos can reflect where your character is at in their personal journey. Same reason why some want more things to interact with in the city, like being able to sit down in a bar and get a drink. Its immersive, and adds to the enjoyment of a game. Or at least it can for some.
I would had wanted my corpo V to get all those crazy tattoos and piercings after hearing he is going to die. So yeah, role playing is a great reason for allowing us to adjust appearance.