It was a tradition. Every year, they would appear: poster after poster with pretty much the same background (dark bluish background, because sinister things were going on) but with a different character in each of them. Posters with the main characters, posters with the main villains, posters with whichever secondary character was slightly more prominent in that particular film. Then maybe some more posters with the main characters. All of them showcasing the characters best very very serious face because, again, sinister things were happening!
By the time the movie actually came out, they all sort of blended together in my mind. And after a few years of this, the posters of the previous years were sort of blending with the new posters also. After all, the kids weren’t really changing that fast from one year to the other anymore, and, honestly, how many posters with the same characters looking serious against a dark background, no matter how well designed individually, can you see before they all look the same?
And yet … when next year comes and we don’t get new character posters I will miss them. So used to seeing them! Like an old sweater that you can’t really bring yourself to throw out, because it was so warm at one point and you’ve gotten used to seeing it in the closet.