Hollywood Hates Sticking to the Source Material

With video game adaptations, I just don't get it.

Books like Lord of the Rings, Harry Potter or even Game of Thrones can get adaptations which usually favour the source material the majority of the time while trimming the fat but with video game films it's like "Woah...no no no, change it all, even the small things, we want a brand new story".

Now would it make the film automatically better? Who knows but at least it would feel like a video game film not some cheap, quickly put together knock off.

It felt like this film was based on Desmond's story but they changed a number of things even the small things like the look of the Animus for the hell of it. The excuse here is "well it's part of the overall universe" but I would have just preferred to see Desmond's/Altair's story on screen.

I just think it can be done, we can have video game films which stick to the source material but it seems like Hollywood just don't want to see it. Hell some games like Uncharted wouldn't take as long since all it needs is condensing down, removing the story elements which were done to add length to the game.