They're actually not just being macho. They are privately acknowledging the fact that if they had to shoot an attacker, there is a very good chance that they will miss because of their own fear, shaking hands, adrenaline etc. It is very unwise to rely on two shots in a situation like that.
Though I am in no way an expert, far from it, from what I have heard the most sensible self defence weapons for situations like that would be something like a glock 19 if you were attacked while going about your business, or a semi automatic rifle if attacked at home, preferably something in 5.56 or .223 so it doesn't damage your house too much. Again, it should have a reasonably sized magazine for all the reasons we've already talked about. As Helgoland mentions suppressive fire could be extremely useful in a situation like that (if you can scare the attacker off or keep him at bay while someone calls the police, or while you get away) so 10 rounds may not be enough, especially if there is more than one attacker. That means the home defence gun would probably be an AR-15 with more than 10 rounds in the magazine. The issue there though of course is that it would depend on whether you were fighting your attacker in a very confined space, all those bullets could wreak havoc and they will still over-penetrate. Nothing is perfect. Another good idea would be a .20 gauge shotgun.