Ah, Hellmouth, we meet again.
Outlander won't be here to save you this time! ...See Outlander's sig.
...Aside
Granted, scarring ingame after precious hours creating your character can be a horrible thought, ruining your work, and for the most part, I agree.
But consider this.
During an epic boss fight with a dragon, and after your grueling efforts you manage to slay it in a cinematic, totally awesome way, but it manages to slash your face, leaving a scar running vertically over your left eye. That, for example, would be badass. A proper war trophy, marking your successful kill. And if this was commented on by the AI in-game, adding to your reputation, your description,
your legend, that would be cool. Now having the option to allow these events to happen would be even better, but the method in which this happens would be difficult. So far the idea that if a wound is 'left untreated for X amount of time' it will leave a scar has the most merit, or perhaps you can only gain scars from particularly important battles with a sworn enemy.
The key point I'm trying to make here is that something like a scar is a part of your character development. Sure, it's not what you'd envisioned when you made your character, but events change and happen in ways we can't predict. I think in that respect a scar would be pretty cool.