I wrote about this in 2013; apparently Microsoft must not be listening to me (the horror!) since the option is still there in the business version of Outlook. In fact, I think it might be the default because I had to change it to "Reply" from "Reply All" today. Why would Microsoft include this option, much less make it the default? I have no doubt there are some people who use "Reply All" every time but surely they have to be in the minority. Besides, that's just bad behavior and it shouldn't be encouraged, even minimally, by having an option for this. Dear Microsoft, it's 2016...stop encouraging bad internet etiquette.