Not to poor cold water on this or anything, but how many audiogames are out there that use FMOD to begin with? I don't know of any, and the last time I
looked at it all their design tools are completely inaccessible. WWISE had a horrifyingly confusing manual, but at least I could use it.
If by design tools you mean their FMOD sound designer, right, it's completely unaccessible. But I still don't understand what that program is useful for...
If most audiogames don't use FMOD, that's mainly because it's quite a complex audio API, but also especially because it's not particularely cheap.
If I remember correctly, they propose a shareware license for 500$, and a full license around 3000$. The audiogame market is so small that it's a quite big investment. Not everybody has the chance to sell 100 copies of 30$ each just enough to refund.
Note that the most powerful open source FMOD competitor, openAL, hasn't a greater success. I explain by the fact that it is again quite complex to use, and by the additional fact that you need another library to manage file formats load/save, because OpenAL doesn't do it (probably because of royalties issues, I don't see any other good reason not to handle it). Streaming songs is also not basicly supported, even local streaming; you have to program it yourself.
In fact you could see that many audiogames, if they don't use DirectX 7, 8 or 9 directly or any of its programming languages specific wrappers, use BASS. BASS is much simpler to use than FMOD, propose most of the same 2D/3D features, and is cheaper. It also supports more file formats through addons. (Price: 125€ for shareware license, ~1000€ for full; still too much imo but already more affordable)
There are 10 kinds of people : those who know binary, and those who don't.