Well, partly it's the power trip.

Really.

We're working with steel here. I mean ... Steel.
Say it with me in the most testosterone-laden voice you can muster, Steel.

For most people steel is immutable, permanent, unchangeable.
Nerves of steel. Man of steel. Bends steel with his bare hands.
Our language and culture are permeated with steel as a symbol of  strength.  

We're also working with fire; which is powerful stuff all on its own...  but the fire we're working with? It's so hot that if we leave a piece of Steel in it for too long, it burns away. Away! Gone! Steel made to vanish! Now that's a hot fire.

As a smith, you take a piece of Steel and put one end into a fire so hot that you have to be careful the Steel doesn't burn away, and when you take it out, you hold in your bare hand a piece of Steel that is glowing, nearly burning at the other end, and with your hammer and your knowlege and your will you turn the Steel into whatever you want it to be. (The hairs on the back of my neck are standing up. Yours?)

When it cools off, your work is permanent, immutable. Unchangeable by the common man.

I don't know about you, but I think that's pretty cool.  

-Carl