I was going to add to my original post that I suspect that it isn't really necessary to reconfirm flights anymore, but I still think it's a good idea. Perhaps someone with familiarity with the res system could tell us if this "check-off" makes any difference in the computer systems for most airlines?

In this particular case, I was glad to have reconfirmed. I was staying at the Four Seasons Istanbul and it only took a minute to ask the concierge to take care of it. Less than 12 hours after he did it, the suburbs east of the city were hit by the 17 August earthquake. Our flight was not until 30 hours after the quake but the airport was jammed with people -- the BA flight appeared to be oversold. Although I suspect most of these passengers did not reconfirm their flight, it was an added insurance I was glad to have on this partcular day.

But I still can't figure out why BA and AA don't communicate with each other on this.