>what is so great about Sound Forge above and beyond what modern day daws can do?
It's not a DAW it's an audio editor. You can easily do low-level editing of one track, e.g., smoothing out single peaks in a waveform that was clipped, or cutting exactly at a zero-crossing.
It also includes very effective processing and effects, like noise reduction based on a captured noise print, volume maximization (called "wave hammer", I particularly like it for processing spoken word audio files), convolution reverb and time stretching. Effects can be previewed in real time before applying them (instead of having to spend time on duplicating the track and applying the effect before I can listen to the results).
It used to include CD Architect for controlling every detail of producing an audio CD. It also has batch processing of files (very useful e.g., if you have multiple files where you'd like to apply an Fx chain and then convert to a different format)
For me, whenever I found a low-level operation hard to do in a DAW, I just exported the track, tweaked it in SF, and re-imported it into the DAW
(these are just the qualities in SF that I've liked for years, others probably see different advantages in it).
I already purchased and installed this, I can now answer my own earlier question about the dongle: It applies only to Samplitude and it is not required. Saving the license to a Wibu dongle is offered as an optional alternative instead of authorizing the machine (note that iLok or eLicenser won't work, only Wibu)