Alderaan said:
A trailer should give you a heads up heading into the film about what you are going to see:
1. Who is the protagonist / who are the protagonists?
2. What is the protagonist(s) goal?
3. What villains or obstacles might stand in their way?
For instance, I have seen that new Mars trailer with Matt Damon several times this season. I haven't seen the film, but I know that if I do see it, I will be watching a movie with Matt Damon's character being the main character, and he will be stuck on Mars and people will be trying to rescue him. Whatever else happens in the film, I have no idea, and I have no idea whether he will live or die or whatever larger point there might be to all of it, so it's a nice mix of setting up the audience but not giving away too much.
This Star Wars Trailer on the other hand tells me:
Explosions! Storm Troopers! Lightsabers! Jedi! Harrison Ford is back!
It's Star Wars!
You see how underwhelming that looks to anyone who isn't drunk on kool-aid?
Well, this was the Monday Night Football trailer after all.
Also, this is a Star Wars movie, it doesn't really need an introduction. The trailer clearly tells us who's the good guys, and who's the bad guys. What's the plot? Same as always really, Rebels vs Empire.
This is Star Wars after all, and they're probably afraid of backlash if they make too many spoilers.
And like I said, this is a the trailer for the general public, so it's definitely supposed to be kind of dumbed down and full of action. It's not really made for fans like us who spend our time on SW forums, that's what comic-con panels and BTS videos are for.
The Martian is a terrible example as it's a standalone movie that has to rely entirely on it's story since it's not a franchise with an established world and characters. Plus, it's based on a book so the story is already well known.