It's not like anyone is trying to be malevolent in this case; it's just something they would never notice. They have the privilege of not having to notice. Now, in day to day life, being left handed is pretty benign, all things considered, and I don't think a right handed person should have to apologize for being right handed, or for not noticing the issues for us southpaws, but neither should they be defensive when it's pointed out to them.
I think all most people are asking for is this: "It was noticed, it was corrected, we apologize, and we'll try and do better next time."
It's as if you couldn't see what's wrong with making the claim, "Niggers are overrepresented on Death Row". It's an objectively true statement, but you still need to change one of the words you used if you're serious about constructive debate.
I think chc in this thread is saying exactly the same thing as me.
Personally, I instinctively ignore people who use it because it makes me think they either aren't serious about having a coöperative dialogue, or are as tactless as the people they're denouncing.
Incidentally, I've seen it around a lot recently. Is it new, or newly popularized?