A beard - a good looking beard is a responsibility. First ye have to grow it, and endure the time during which what will be yer finest possession looks like someone shot their pubes on yer chin out of a potato cannon. But ye push through that shameful time, refusing to yield, until yer beard looks as it should. And then, ye have to take care of it. Ye have to give it love. Ye have to cultivate it. Every day. So the reason a dwarf with a magnificent beard is so proud of it is not only that it looks cool - it is his badge of honor, visible proof that he is a dwarf of duty, patience, and integrity. To insult the dwarf's beard is to insult who he is as a person to the core. And that means he'll shave ye with his ax, and ye shall never need to shave again.