Just because something looks the same doesn't mean it is the same. GF themselves claimed they had to remake the models from scratch, and while there's some argument about what "from scratch" means, they absolutely had to change the model format and remake every single texture, so there was some work that had to be done. Less than people expected, but enough to be actual work. GF have had some fucking awful communication with fans here, which is why people are so fucking pissed.