Why are there so many Payday Christmas DLC giveaways?

I think there's a sale somewhere... oh, yes, it's on Steam.

They were 11 cents, and give you a 4-pack.

For 19 € cents you get 4 copies, 3 to gift, this DLC gives you a Soundtrack and Santa Claus masks.

Payday Christmas DLC is 19 cents

http://store.steampowered.com/app/267381/

Ok, the 4-pack thing makes sense, then. But I wasn't just talking about the past few days of the summer sale, I've just seen this particular DLC so much over the past 6 months it made me wonder, but I guess the 4-pack thing probably applied to that, as well. Thanks!

1)should be free
2)nobody wants it
3)absolutely worthless (see #1)