The problem is we have no idea how Houghton Mifflin selects the authors to edit the anthologies. All we know, from reading the articles, is that each selection is made without knowledge of the other selections. Meaning, at no point until all selections were made could someone have said, "Y'know what? These are all white dudes. Let's ditch Neil Gaiman and pick some chick."
And wouldn't you think it's MORE insulting to be picked just because you happened to be a female than because you really were regarded as the best in a given year? "Yeah, we were going to go with Gaiman, but we had to pick a woman so you're it." Sure, they don't have to SAY that, but if that's the truth, how offensive is that? I'd just rather they went with the white guy.
I certainly can't argue that the men they chose aren't deserving of the honor. I don't know all of them, but I do know Gaiman, Lee Child, David Eggers, and Bill Buford. They're giants in their fields, and men I deeply respect as authors. So it's not like they passed over a woman or a person of color to pick some schlub.
As a final thought, in prior years women and people of color have been editors. Three last year were female (and Amy Tan's a 'double dip'). As this "all white guy" thing is not a persistent pattern, I am indeed inclined to dismiss it as a coincidence and get on with my life, bra unsinged.