The legs are essentially bonus damage. Any damage done to the legs without the debuff reduces that bonus. It's important that ranged dps do not try to maximize their personal dps by multidotting and burning down legs that are 35yd away, as doing so reduces the overal dps of the raid.
can you explain what you mean by this? i could be misunderstanding how it works, but each leg's health is equal to 3% of the boss's health, and the boss loses 3% when each leg dies.
therefore, i figured damage done to the leg is exactly equal to damage done to the boss (ignoring the leg buff for a moment). so if you can cleave / multidot, it would be a dps increase; but if you are punished for target switching, it's a dps loss.
when you figure in the weak points buff, it's an obvious dps increase to attack the leg if you are in its circle. but i don't understand the reason that cleaving / multidotting distant legs is a bad thing if you're not in the circle?