I still think a movie like this works sort of like the Expendables - having all the names on it is a bigger draw than just having the one name.
Or, more topical, it would have been like having Avengers posters that only mention Robert Downey Jr. (or even more specifically, having a poster with Chris Evans or Samuel L. Jackson that says "Robert Downey Jr.).
Or, more topical, it would have been like having Avengers posters that only mention Robert Downey Jr. (or even more specifically, having a poster with Chris Evans or Samuel L. Jackson that says "Robert Downey Jr.).