Trailers and Promo art that is actually an honest representation of the film. They might get bums on seats, but misleading trailers will end in bad reviews.
For a cash grabbing pop-corn & explosions film (*cough Transformers Cough*) that might be enough. Money talks.
But its not acceptable for a franchise looking for longevity over $$$
Also, a trailer should give you a glimpse into the film, not a summary of the whole bloody plot!
Im not having a dig at Covenant here, there are many franchises doing this to jack up ticket sales. But honestly if the next Alien film was to have no Xenomorphs in it for example, tell us that. Let us decide and get intrigued by an Alien film with no Aliens, rather than pretend it did.
Maybe its why Prometheus did better (overall) than Covenant in $$ and Ratings. Honesty and intrigue.