I really appreciate what you wrote here, Andy. I'm a developer first and a DBA second. Some years ago I needed to learn how to write ASP.NET Web Forms apps in a more structured way. I always learn better if I have a project to practice on. I have a fairly large video collection, and so I designed a database and then started writing the ASP.NET Web Forms app to run against it. We've used it at home for years, seeing how long ago we watched a particular movie we own, what are the latest films we've watched, etc. And I've used this over and over again. I wanted to learn Windows Presentation Foundation (WPF) so I took the same database and did it again in WPF. And more recently I've been working on learning ASP.NET MVC, so I've started the project over again a third time. Very much like your CD example.
The bottom line is that this has proven to me to be literally invaluable. So I think having something like this for the DBA to learn new topics would be great! I could use learning how to do SSIS, since in my new job I have to maintain them. But I hate to make any major changes for fear of screwing up production. It would be fantastic to have a test database where I could experiment to my heart's content learning SSIS. Would I use it? Yes.
Kindest Regards, Rod Connect with me on LinkedIn.