It's been about 5 years now that I connect only the IDE of my optical drives. Even in Win98, never had a problem. The sound card manages anything that must be output to analog.
I'm wondering, just like you, why some drive still come with an analog audio output. Besides, the quality of the DACs (digital to analog converters) in optical drives is (for obvious price reasons) of low quality, so it makes no sense at all to use them... in my opinion of course.
For ripping, would it be data or audio, the process is aways 100% digital anyway.