Because they left us with a pretty huge cliffhanger there. Actually multiple cliff hangers (spoilers below):






































So we have Zombie Thanos waiting in Wakanda with all the infinity stones except the mind stone which they are bringing to him. They also cut away at the beginning of a huge fight between Hulk and Zombie Scarlet Witch. On top of all that we don't know the origins of the virus, or if it was engineered (I think it was). I'm definitely looking forward to more of this story at some point...