Unfortunately, I know next to nothing about D3D or OpenGL...
I do wonder why the game appears to work fine.. I haven't noticed any anomalies in the graphics output as far as I can tell. If this is also the case for those 3 other games, wouldn't an override via the registry for this value not be an acceptable solution?!
No
Wie can't lie about our abilities. It may fix those 3 games, but then 20 other games will start using the broken functionality and break.
As for a registry key, I don't want this to become a mess-with-the- registry-fest. Things should work without requiring custom registry keys(or DLL overrides for that matter). This may sound cruel, but sometimes keeping things broken is the best way to motivate people to fix it.
Unfortunately as you say, this vertex pipeline replacement stuff is a quite advanced topic, and D3D is pretty advanced by now so there are very few bugs that are an easy job for beginners to fix There are certainly no weekend jobs left.