Hey, the amount of time people look at the artwork is about as equal to the amount of time they'll watch a movie. I would even say that the artwork for the films is looked at more often than the films themselves.
I treat posters/cover art as an art form in on itself. Even though it's supposed to reflect the film, posters can really energize someone when look at it. Unfortunately today, a LOT of poster artwork has been doing the bare minimum of trying to convey what the movie is about. Take Star Trek (2009) for example.
See? It's just some guy's head looking down on us. Does that really showcase any of what Star Trek is like? Here's one of my favorite Star Trek posters.
I LOVE this poster for Star Trek VI. It's got space, planets, the Enterprise at warp and a Klingon looking up. I would want to see this movie more than the one that only showcases Mr. Bada** face.