It seems they have come to the conclusion that the main effect of volley fire is its impact on morale, hence a different mechanic for handling it, although I’m not convinced they have got it right. It probably works best when targeting Irregulars, I’m not convinced they have it quite right for targeting Militia. If you look at the AWI, it would appear rebel militia feared a bayonet charge more than a volley (which is not to say a good volley wouldn’t break them, but it’s my understanding that it was fear of the bayonet that most unnerved them).
But then M&T2 appears to get a few other historical things wrong, for example the treatment of light infantry. Why British light infantry has the same aggression level as American militia is bizarre. Light infantry were trained for speed and aggression, closing with the bayonet was just as important as a skirmishing type role. Not only that but American militia rarely had bayonets and were generally expected to stand their ground rather than go on the attack and yet in M&T2 they are considered as good in hand to hand combat as the lights.