Sure you may ask why!
The reason it's important is ADC's have large amounts of noise shaper noise, starting at about 25 khz; this increases rapidly, so the higher sample rate has a lot of out of band noise. And this noise is artificial, and because it is random, creates noise floor modulation in the analogue electronics. So filtering this noise out makes it sound smoother. The higher the sample rate, the worse it becomes, and the more obvious the HF filter becomes.
Davina, the ADC project, won't suffer from this, as the noise shaper noise will start increasing above the 768 khz sample rate. It's one of the many benefits that Davina will have.