Once in a while, I forget to explain my edits. Other times, I find I've made a typo, or that annoying bug that prevents mid-sentence changes manifests itself and I don't see that in time. I would love it if I could just go back and explain myself better, just as I can edit almost anything else on WT--comments, G2G posts, etc.
And by the way, I wish everyone would explain their edits. It is not only helpful to others, but useful for ourselves when we go back to profiles we've worked on and want to figure out what we've done.