Info that's released officially is usually fair game but it could have been hidden in the title. I can understand why people are a little pissed off.
The argument that "it's in official promotional material, so it's fine" doesn't really fly. The one and only objective of promotional material is to put butts in seats. To tell tickets. To make money. And to accomplish that goal, the studio has has no qualms about spoiling details that would be better experienced in context, or even to willfully misrepresent the film. Preserving the ideal experience for the audience is not a priority or even a secondary objective.
Go back and listen to The Official Lost Podcast sometime, and one of the recurring things on that show is Lindelof and Cuse expressing frustrating at things the network chose to use in promos. Just recently, Simon Pegg was out there telling people not to watch that final trailer for Star Trek Beyond. In Iron Man 3, the action sequence with all the old suits joining the fight was featured regularly in trailers, but when you watch the actual movie, you see that it was conceived and cut for that to work better as a surprise. You only see one suit on camera at first, then the shot expands to reveal an entire army. It's a cool moment that is rendered inert by commercials, so that clearly goes against the intent of the creators and undermines the audience's ability to have the best experience with that scene.
But the magic thing about this debate is that no one has to agree with a single word I'm saying here, because spoiler tags exist, and if people don't mind this stuff, there are no rules against posting it and nothing stopping people from choosing to uncover spoilers and read them. But denying that choice to people who do care is pretty shitty.