It wasn't exactly useless. It made newer gpu's go into full gear instead of being stuck on idle. With that said, it doesn't really boost your framerate nor slow it down.
To elaborate: It was slower than the other texture decoders, created issues, and was a pain to maintain the code. So they dropped it.
Now I should point out that LLE audio and efb copy to ram are the default settings in WW for a reason. They are needed to fix certain issues. So whatever you do please don't complain about those issues as so many others have.