A3D was removed due to be unsupported on Windows, not sure what the state of EAX was on the 3 platforms, but it got removed aswell.
EAX relied on A3D to work properly, so both were disabled by design.
I have used the EAX features since my first Creative sound card. Calling this an exploit doesn't sound right at all. Sound in HL1 and CS sound so dull now. There is no distinction of where the audio is coming from now and it just sounds like stereo sound coming out all my speakers in my 5.1 setup. I can't believe this sound feature is being called an exploit. Creative still supports EAX features with the Creative Alchemy application. The tram ride in HL1 sounds horrible, as do other big moments in Hl1, and the sounds in CS1.6 are just as dull. Please consider putting this feature back in.
Nothing extracted yet.
When I go into the audio options both EAX and the other checkbox are missing.