There are several reasons for replacing the stock steel brake pedal, but probably the most important one is to protect the engine. The brake arm is steel and it will deflect inward if it or the pedal itself is bashed by a rock. That turns the inside surface of that thin and hard steel pedal into a hammer and your clutch cover into an anvil. Since the clutch cover is cast alloy, it'll crack when impacted like that. This, of course, may well strand you out in the middle of nowhere with an engine that has dumped its motor oil out on the ground. The solution is to replace the thin steel pedal with a thicker aluminum one. Being that the material is softer and that the load will be spread across a broader surface, the clutch cover is less likely to be damaged.
KTM-Husaberg has an accessory pedal, but if you'd prefer to support an real American entrepreneur, try this on for size: http://www.systemtechracing.com/category_s/247.htm. I have one. It's a great product. The teeth are replaceable, and a full set of replacements are provided.