The primary purpose of the lever is to make the clutch pull of the bike longer for a smoother engagement and less lever force required to disengage the clutch. This prevents stalling at lights, jerking between shifts, etc. It also makes your left hand happy from the reduced tension on the shifter lever. The bike generally becomes easier to ride, even easier to drag race.
Surely someone on here knows how to cut and weld a few bits of metal together