Not at all. At least not for me. It's only in hindsight that everything appears obvious.

I spent a considerable amount of time trying to figure out the track textures. It was only when I looked at the game in an emulator again (psxemu[1], which comes with nice debugger that lets you record frames and single step through draw calls) that I noticed that the track faces are subdivided at run time. This gave me the clue to look for textures in different LOD levels.

Still, it feels great once you get it working. Reverse Engineering is like solving really rewarding puzzle!

[1] http://psxemulator.gazaxian.com/

Very interesting. I did this, as well. It was possible to put the Wipeout 3 CD into a CD player and play the tracks as though they were audio files. Realizing this, I used a simple audio ripper to extract the audio files. This was (I think) around 2001 or so.