I think most experienced refers will suggest you never dose anything that you don't test for. Not sure if there's tests for iodine or not. I've read some mixed opinions regarding iodine. Some say it's beneficial...a few say it's harmful and most say it's benefits haven't been proven or substantiated. I'm sure there's a lot that I haven't read about it so take what I say with a grain of salt...I prefer Instant Ocean...lol. I'm sure others, who are more knowledgable will chime in.
I have no issue if one decides to dose Iodine as long as you are testing for it. Many plants do use iodine and suck it up like a sponge.
Ron Shimek did an assay on ~ 20 reef tanks and found that in all cases Iodine was above NSW. The bar graph at the very end on the right is I = Iodine. And 1.00 = NSW. All I tests where above 1