I suppose it's somewhat understandable. Your average gamer spends most of his time playing on his console alone, thus the easiest way for him or her to find other players to play with is to go online. Gone are the days that players routinely meet at a friend's house to play together. More often than not people just utilize whatever online options the game / console supports and then they go from there.
The Dynasty Warriors series has certainly been a guilty pleasure of are over the years. They practically invented the crazy button-mashing bonanza genre for more "modern" consoles. Although when you think about it, these games probably trace their origins back to classic titles like Double Dragon, Streets of Rage and Golden Axe. And that's never a bad thing.