You'll have noticed, firstly, that when you sneeze in company it is unlikely to be followed by a chorus of Bless yous anymore ... Given, however, that the politeness of this gesture has always--at least in my mind--been outweighed by its considerable fatuity, it's difficult to think of its absence from common manners as much of a loss.
But you might have noticed, too, how few people excuse themselves after they sneeze now. They just explode at you, or near you--blasting a hole in the flow of your conversation, or shattering a peaceful quiet--then mop at their noses, groan perhaps, and go on as though nothing happened. (You, needless to say, are expected to do the same.)
The reasoning here is, I suspect, that because a sneeze is involuntary--because it is not your fault--you should not be held accountable for it. But see how the litigious mindset--our ersatz common sense--veils a significant portion of the same truth: that while a sneeze may not be my fault, it is still unquestionably my responsibility.