Trailers and perhaps more importantly, teasers are able to produce a great amount of anticipation towards a movie. They are geared to appeal to the largest demographic possible so studios send footage to various trailerhouses to appeal to women, children, the male demographic, etc. Let's say the average age for executives in these houses are 25 to 35. Let's look at their point of reference: the last 15 years of movie marketing. Which is to say, not very strong. This is why we are getting bombarded with the same stuff.
There are some more of the creative people out there though. Just watch what one youtuber did to the terrifying film The Shining:
With the change of music, the voiceover and the clever cutting, what was once terrifying is now turned into an upbeat family drama.
Hitchcock and Welles would even introduce their movies Citizen Kane and Psycho when they cut trailers for those respective films. But then again, they had enough creative control to get away with that.
Trailers from the 70's and the 80's knew that if you show all of your money shots in a trailer, what would be the point for a person to pay money to actually see the movie. That philosophy is out the window nowadays. The advent of MTV and all the fast cutting has trailers packing as many shots as possible.
Perfecting the art of the trailer depends on how much information you want to unveil to the audience member. For example, watch the difference between the teaser and the full length trailer for Terminator 2:
Now imagine if you just saw the teaser for Terminator 2. You would have no knowledge of which terminator is bad. We already know Arnold played the villain in the first one. This would make the scene where each terminator turns the corner in the mall hallway all the more suspenseful. To just go with this teaser, something that shows nothing from the film, would be a big chance. Within the full length trailer though, we are given the information that Arnold is the good guy.
You can also have the flipside where you cut a trailer for Drive to make it look like an action movie when it really is a slow, methodical existential thriller.
The whole "give away everything in trailer" deal hurts genre flicks the most. Namely comedies. The substandard "cramming in all the funny jokes" in the trailer. Once you see a joke, it's not really as funny as the first time you see it. When you actually sit down and watch the "hot new comedy", you realize that the jokes that actually were funny were ones you saw already in the advertising for it.
A remedy for this problem is simple but rarely happens: be creative and work with what you have. Case in point: A Serious Man. This trailer could have been a black screen with the words "The next Coen Brothers film" and I would have seen it. But it went so much further. Looping sound effects and pieces of editing give this trailer this gleefully subversive vibe. I remember people getting mad at this trailer and call it awful marketing. It's the exact opposite. We've just been conditioned to so many conventionally cut, by the numbers trailers that anything creative causes awkward gawking.
Editing is about manipulation. Once you edit a frame, you are manipulating an image. This ties into marketing and advertising because you want someone to buy your product. So why not use it to its full effect. Kubrick knew this. Just watch the trailer for A Clockwork Orange and study the rapid cutting and quick words like Witty, Metaphorical, Sardonic, Comic, Bizarre and Musical flash across the screen. Coming back to The Shining, you can make it as simple as possible and have nothing be shown. Just an elevator with blood coming out of it. That's it. All we need to know about the movie rolls across the screen is supplied in three forms: the music (giving the foreboding tone), the visual (this pegs it as horror) and the words coming across the screen that say "A Film By Stanley Kubrick."
Since we are on the topic of trailers for horror movies, I might as well discuss another tiresome trend. Every horror trailer of the past 6 or 7 years could seamlessly bleed together. Here is the structure:
Introduce audience to protagonist
Show them how conflict is introduced
Use the soundtrack to create moody atmosphere
Title card saying "From the Producers of (most likely Paranormal Activity and Insidious) or Directors of "So and so"
Montage of several scenes that either lead to fuller "scares" in the movie or random insert shots meant to provoke warning and a foreboding tone
Ratchet that intensity up throughout the montage while soundtrack crescendos
Then, that one extra scene. The one where the soundtrack and dialogue cut out and everything is silent. The final jump scare which is most likely the biggest jump scare of the movie, tagged at the end.
Cut to Written By and Directed By
We've all seen it. Even the trailer for The Babadook attempts to make it look like a milk toast, generic horror movie. Nobody really knew who Jennifer Kent was before that. So if I were to share the trailer with someone and urge them to see it, they would say it looks generic. How does one correct this? Well, for one, knowing that trailers are cut to appeal to the widest demographic. Now Kent is first time director. She doesn't have enough clout as more established directors.
Spielberg, Abrams and Nolan on the other hand are directors who do have enough clout to get this kind of control on their projects.
The latest example this is Star Wars Episode VII. I knew I was going to see this movie in the theater. But after the second trailer, I was blown away by just how perfectly edited the trailer was. It gives fans everything they want (Instant nostalgia when Han and Chewbacca are revealed) while at the same time saving a ton of footage until it hits theatrically.