audience will not reject flaws in the visual esthetics of a movie as easily as they will reject a film for its poor sound quality. For instance, if the dialogue tracks of actors voices are too low it brings to the attention of the audience the fact that the actors voices were recorded. This can negatively affect their suspension of disbelief which reminds them that they are watching a movie, and not experiencing real life. It will ultimately affect their opinion of the film for certain.
The sound of a movie can determine whether or not it will be a success. The Star Wars movies owe much of their success to the sound designers and technicians who worked very hard to create alien sounds that complimented the visuals perfectly. They made those movies sound believable, literally, and that is a very hard thing to do in general when it comes to science fiction films.