Armies have their good and bad points. For a long time in the North and South community armies have been able to keep the mod alive as long as it could be, the reason for this is that they ensure that a stable player base can be handled in an efficient manor also when it comes to events it also ensures that people will go the the event in the way that people can still play and enjoy themselves as there are people to play against. A lot of people also do enjoy the RP that the armies can provide, this includes the fact that there is higher command included allowing people to make complex plans which could be efficient in the way that the battle is played out which can only be achieved through brigade and corps command.
However, if the armies work the same way as they are in North & South, they leave little to no room for independent regiments, they also can split up and certain armies can go into isolation in the community like the UA and DA, reminding you of the fact that the situation used to be a lot worse than it is now.
Personally, I would like there to be armies in Whigs and Tories, however, I would not like to see them turn out to be the same way we see in other mods.