Read other letters about this article
It is NOT simply about the fact that the word "butt" (oh, horrors!) was mentioned. It is about reducing her to her "exoticness" at best, and summarizing her (more or less "traditionally black," so to speak) figure as somehow "ghetto" at worst. Last I heard, "ghetto" was not a compliment to anyone over the age of 25.
And I'm sorry but Michelle Obama simply does not have a prodigious ass. Undeniably present, yes, but especially prodigious, not so much. We do not have anything like a case of steatopygia, here. (Yes, I've actually felt compelled to go and LOOK THIS UP now, to see if I have a viable thesis. I have felt the need to go and VERIFY the size of the First Lady's butt and formulate a thesis about it.)
If she had an actual big butt, the discourse would be different, and the usual letters-column suspects would be up in arms about the article "glorifying fatness while the fat use up too many resources and health care" or other such garbage. But we don't wax rhapsodic about THOSE sisters of ours.