In this mod, you get on fire the moment you step into the nether, meaning you better stock up on fire res potions.
Q: "tHe FiRe AnImAtIoNs Is BlOcKiNg My FiElD oF vIeW aNd MaKiNg It HaRd To TrAvErSe WiThOuT fAlLiNg InTo LaVa!" - average twitter user
A: Yes, the fire animation is there which amplifies the difficulty (and hence deadliness) of your experience in the nether thus fulfilling the mod's purpose. Plus you could always get a mod/texture pack that lowers the position of the fire animation, make it transparent, or straight out remove the animation if you want to. :)