Boob belts *are* iconic. That point cannot be argued.
However, a woman whose fashion sense is completely absent, who was as likely to wear something mildly attractive as something hideous, is hardly a fashion trendsetter.
I think the narrative that Michelle is an unsurpassingly beautiful fashion symbol is just more of the same tired old liberal propagandizing. Like the narrative that all conservatives are racist sexist bigots, it has little basis in reality.
I think they wanted to propagandize everyone to believe she was the ultimate First Lady. Now If you Google "fashion icon" she is probably near the top of the search results. It's an example of Fake News.
Now, contrary to what some here may think, I believe that there were times when she could look striking, but often she looked like she didn't care what people thought about what she wore, and I guess in her position, that is iconic. I am looking forward to the next four years, at least!, of fashions from the White House, Melania's and Ivanka's!