You need both for different purposes. I have a bunch of different mixers/VCAs for both cv and audio in my modular, and I have a Tascam Model 24 on the way that will allow me to fine tune final outs, and record many different outs into an SD card all on their own track to then put into Logic later. People who think you can just plug modular stuff straight into an audio interface without any drawbacks are smoking something; even audio out interfaces within eurorack can be quite different--my Vermona TAI-4 has transformers for both in and out that make a sort of pleasing saturation that make the exact same sound source sound better when I output it compared to more generic output modules (or none at all).