There are a lot of reasons the 2015 version of Fantastic Four failed. But one of them might have been cutting all of the elements of the original story idea's massive and completely bonkers battles. Screen Crush has a long post-mortem on the movie, which includes an interview with Jeremy Slater, who wrote some initial versions of the script before Josh Trank and Simon Kinberg put their final stamp on it. The article's worth a read just for all the details Slater gives on the original idea, including a very cool Baxter Foundation.
But the part that stands out the most is his description of all the stuff that got cut:
In addition to Annihilus and the Negative Zone, we had Doctor Doom declaring war against the civilized world, the Mole Man unleashing a 60 foot genetically-engineered monster in downtown Manhattan, a commando raid on the Baxter Foundation, a Saving Private Ryan-style finale pitting our heroes against an army of Doombots in war-torn Latveria, and a post-credit teaser featuring Galactus and the Silver Surfer destroying an entire planet. We had monsters and aliens and Fantasticars and a cute spherical H.E.R.B.I.E. robot that was basically BB-8 two years before BB-8 ever existed. And if you think all of that sounds great...well, yeah, we did, too. The problem was, it would have also been massively, MASSIVELY expensive.
So expensive. Also, possibly alienating to the new fanbase that Fox wanted to court. And definitely much more like a comic than Trank's vision. It was never to be, but way to be the one looking at the stars from the gutter, Slater.