Sadly, as the bracket ages many don't have time to queue at the peak times anymore, hence the slow decline of the bracket, while when it was for retards who liked farming lvler's have moved to the less competitive scene lvl 20s. Although the addition of xpoff brackets being separate has made the bracket more enjoyable when queues do occur, and the increased quality has derived into better players improving. This exact same thing happened in the introduction of cataclysm but those free to play accounts only lasted 10 days if I recall correctly, hence nothing really farm able and had to make the players at the 19 bracket improve or join endgame.
But, with the constant ability to play for free, many will simply just prefer the easier and less skillful option, because these are the kind of people that demand an easy mode on darksouls. Tough times create tough people, eventually or even with a large sum of money dropped into say twink cup, could arise with more players wanting something better. I promise that if any somewhat decent lvl 20 played a organised wargame they'd enjoy it far more than any pug, and they'll notice this eventually.
