Preamps built Into DACs

Only good reason is sound! Not any other reason.

Preamps, great active preamps, are a must for me. Without it music is
simply not as musical to me. So preamp builders please build on! To my
ears a proper stereo system needs a great active tubed preamp.

To me, I would be wasting money on my system not having my active tube
preamp. So yes, stop putting a volume knob on all those DAC's so when I
buy one I'm not wasting money on that volume knob.

To each his/her own and this is just my experience and preference. Listen
on!

Charles1dad, you said it very well and my experience is the same. No active preamp in a system is wonderful sounding to some, but I have always found the resulting sound cleaner, lighter and lacking in body, weight, natural tone and impact. No active preamp systems seem to provide more detail and can certainly be quieter, but over time I became aware that the perceived transparency and detail was really a result of other important musical cues being missing.

I think it comes down to the type of sound one likes. Both are ways to build a system and they yield different results - sound of music. As the post above states our actual experiences differ because we all like and are pleased by different sounding systems.