I posit that, in a world where people are always petitioning heroes to save them, the peasant folks will pick those heroes who look best. So over thousands of years of adventuring, there has been a trend toward beautiful heroes. Magical healing could very well take care of scarring, and no doubt there are spells -- not quite so prevalent in the PHB, but logically they'd exist -- that would be magical plastic surgery. And let us not forget exotic armors, such as the
Chainmail Bikini, which require specialized training to wear effectively.
Sure, adventuring is a matter of life and death, but if you can't look good while doing it, why bother?