There are actually a lot of white women that are built like Michelle Obama. Being pear shaped is actually fairly common.
The problem with the way she dresses is that she often chooses clothing that emphasizes that disproportionality.
And then there is the issue of her extremely expensive wardrobe. I know several women whose familial net wealth is similar to that of the Obamas, and none of them routinely wear outfits that cost thousands of dollars.
People come in all kinds of shapes. All of them can find clothes in which they look tidy and dignified, if they try. Whatever look Michelle Obama is reaching for, it’s generally not “tidy and dignified”!