I worked with them for years, mostly UniVerse and UniData. The short answer is no, I don't think there is a reason to base any new work using a Pick based MVDB. Don't get me wrong, I see some value in what they were trying to accomplish, but today there are NoSQL solutions which are far superior to how these old Pick style solutions were built. File corruption was a real pain and normal reality, searching, sorting and managing the data took a full time DBA/SysAdmin for even smaller implementations. Mixing the language and database as most of these systems did too was a mess to manage, version control was a pain usually, value typing was not good and error handling was always a challenge to do it even just ok at.
To be fair, I do see some elegance in how they work, but just the trade-offs today aren't the same, so IMO there isn't a good reason to use them when we have graph databases, the modern NoSQL solutions and SQL for that matter.
Essentially, a current document database does more than these solutions can and more reliably.
This is also why, I didn't see NoSQL solutions, like Mongo et al, as something so revolutionary when they came out, to me they are just a modern twist on things we have had for decades.