For those crying how Ubisoft 'deliberately' removing content from the game to make us pay extra for it, please, cut that shit out.
When you make a game, things get cut for various reasons; mostly its time related. You got all the ingredients, but you don't have time to put it all together, so you put the ressources that were wokring on it on other things, the things that are nearly finished, to actually make them better. There's a lot of games where stuff is left on the cutting room floor and sometimes, these decisions are taken mid-production and for this DLC maybe they decided to finish the work that was started, now that they had the time since the game was shipped. It's not unheard of.
As for ACII, the entire DLC content will be downloadable, it's not a key that weighs 4k, but an entire chapter, with another one coming soon after it. For 60$, you got 20-30 hours of gameplay and the game felt complete. The 'missing chapters' that were talked about in the game could've been a nice like joke and left alone. But for 4$, read again, 4$, you get a brand new chapter that's surely gonna be as good as the ones in the original game, so please, go cry somewhere else.