She is extremely bright. Such folks, like everyone, miss things and are naive to some stuff. Bright folks differ from dolts in that the former are naive to far less than non-bright folks and they don't often make unforced blunders, yet they do make them. Bright folks also generally, but not universally, availing themselves of their intellectual acumen to subdue their hubris and self-confidence; they do so by at least thinking about and confirming the validity of the stuff they are of a mind to say, or they qualify their remarks to make clear they have a measure of uncertainty about the factual and contextual legitimacy of their remarks.
Ms. Kelly's blackface comment is an instance in which a bright person simply didn't do that. And, well, for her, as with all bright folks and with celebrities (bright or not) of one sort or another, the bar for not making blunders of the sort she did is no different than it is for the rest of us, and she didn't rise to meet it. What distinguishes Ms. Kelly from the rest of us is that having limited visibility, most folks mustn't endure having their blunders and ignorance made manifest to the world.
Ms. Kelly is experiencing nothing the rest of us don't. Surely there's someone whom you know/knew whose remarks showed the person unworthy of your forbearance and you expelled them from your orbit. Well, that's what's happening to Ms. Kelly. It's just that "everyone" is seeing her expulsion whereas few folks are aware of your having removed "so and so" from your good graces.
Too, my remark about ignorance shouldn't be taken as my implying she's generally ignorant, but rather that I think on the matter of blackface, at least at the time, she was, if her apology is to be believed -- "I
learned that given the history of blackface being used in awful ways by racists in this country..." -- she was naive about blackface and its implications. Either the woman knew before she made the remark, in which case her saying she learned was untruthful, or she didn't, in which case she was, at the time of making the remark, she was ignorant about the nature of blackface, its symbology and effects.
In light of Ms. Kelly's apology, I wouldn't postulate that she was aiming for "edgy"+something else, but I'm willing to agree it's to some degree plausible she was. If she was going for something of that nature, she'd have been yet another TV personality who attempted to do so and inaptly did so.
FWIW, I found Ms. Kelly's mea culpa acceptable. She apologized by taking full ownership of her naivete and correctly identified blackface's execrability and cited it as etiologically germane to her initial expression's unjust immorality. (She clearly didn't mean "wrong" in a factual way because in the mid-to-late '70s and early '80s, a child of no particular renown costumed in blackface would have drawn little to no outcry. Of such a child, some may even have thought the getup cute or funny.)