That's because Christmas isn't that big of a deal in Japan.
Also, to echo some peoples complaints so far, DT has had several bits of High Tier content now. Savage, Extremes, Unreal, Ultimate, and now Chaotic. Whereas mid core players are left leveling everything or simply playing other games.
I've been playing since 1.0 and honestly im starting to get bored and might unsub if it doesn't change. While i appreciate the extra time its had on devs to push out content, it really doesn't help with that extra month between patches.