What many fans may identify as the crime, is the implication that Trank and the writers aren't using anything from the history of Fantastic Four comics to create their new vision (beyond the character names and basic characteristics, powers, etc.). However, there is room here for some debate as to whether or not breaking free of the source material is a good move.
Whatever fans may want to say about fidelity to source material, the actual numbers don't lie: Fantastic Four has had some of the lowest comic book sales of any Marvel property for quite some time. In other words: the source material isn't that popular. In that sense, avoiding direct emulation of something that is clearly unpopular is more pragmatic than it is heretical. It's also funny to hear Mara say that the film isn't adhering to anything "already published"; there's room in that statement to assume that, if successful, The Fantastic Four movie reboot could end up influencing the comic that inspired it.
Right now, it seems that Marvel's handling of Fantastic Four (a low-selling comic book they pay to produce, servicing a movie whose profits they don't see the bulk of) is an uncertain one. It's not out of the question that if Josh Trank and Co. produce a blockbuster hit out of their revised vision of the super team, Marvel Comics wouldn't mold their book after it, in order to maybe capitalize on better sales. It wouldn't be the first time a successful movie altered the nature of its comic book source material (see: the black leather invasion within X-Men comics of the early-to-mid 2000s) - the key is making the movie a success in the first place.
Hopefully we find out more at SDCC 2014 next week, where The Fantastic Four could potentially make a surprise appearance and finally reveal footage that might turn the tide of low expectations and fanboy hate. We'll see (maybe).
The Fantastic Four will be in theaters on June 19, 2015.
Sources: Esquire Latinoamérica via CBM