Maybe it's different for fans of the comics. I don't read the comics and have only seen the first movie. While it's definitely darker looking, and apparently the origins are different, I still relate it as Fantastic 4, as the basic premise is still there. If a random movie came out with a dude made of rock and another of fire, everyone would call it a Fantastic 4 rip off lol
It may be a horrible fit if you shove the comic into it, but as a movie about 4 superheroes, you can't possibly know if it's a horrible fit or not. That's why it's an adaptation.
And people can criticize how a group of people chooses to adapt something if they feel like their adaptation doesn't fit what they see the characters as. It's a perfectly valid complaint. You might not care that it doesn't feel like the Fantastic Four, but there are people who are actually fans of it and don't want some re-imagining, especially when they haven't made a F4 movie that fits the tone of the comic yet and they think that the tone that the comic has had for decades could be made into something amazing on the big screen.
It's ridiculous that you'd put "Shove the comic into it" like it should be some kind of hassle. It's the source material, it should be representative of the comic. You never see people claiming that people who want a faithful adaptation of a book are "Shoving the novel into it." It should be like the comic, they wouldn't have bothered keeping the name and rights if the comic book stories weren't worth something. Instead they chose to adapt one of the least memorable FF runs.
How do you know this from not watching the movie?
Because it already looks like the exact opposite of what makes the Fantastic Four interesting to me. The fact that I've constantly heard that this is supposed to be a more "Grounded" take on Fantastic Four never helped, and this trailer looks to be following this exact line of thinking. Grounded is the last thing Fantastic Four should be.
Are you honestly telling me you've never seen a trailer for something and thought that the movie/game/tv show looked bad from it? I find it hard to believe. If a trailer has the ability to hype people up it shouldn't be surprising that a trailer can also sour a person on whatever they're showing.