my take on V's pov is that the body is best at getting what it needs and maintaining internal balances. this requires the tools being avaliable to make adjustments one way or another. i see this with acid/alkaline issues as well. give the body a balance and let it fine tune it for ya.
the thyroid can get too much iodine. otherwise, the Iodine pills for nuclear emergencies would not work. their uptake is self limiting as well. interestingly, with such a mechanism in place, where did the reason for such a process arise? there must be a common comestible in the past which could provide such large dose of Iodine all at once. think about it.