What I've been able to find confirms your suspicion. Primarily, there were two motivating factors for the group that switched to this format: data security (DAA files can be encrypted/password-protected like a Mac disk image) and price (the other ISO creation/virtual mounting software vendors wouldn't match the price of PowerISO).
It looks like the Windows-centric workplace strikes again! I could suggest switching to a secure archive format, but the virtual drive system actually works really well for this type of data (lots and lots of compiled research, without getting too deeply into specifics), whereas data archives would have to be extracted, etc. I'll just use a Windows PC for these particular files, I suppose. Thanks!