It would be useful to have folder metadata. There are many uses for this but at a high level you could definitely folder types (strategic vs. operational), provide folder owners etc.
Please check the comment
AdminStructure Team (Admin, ALM Works) commented
We are working on custom item types right now. In the first implementation it will be something similar to folder, but with possibility to define description. Do you want to be able to add your own specific parameters?
Also we have Notes column (https://wiki.almworks.com/display/structure/Notes+Column), you can add some comments for specific row (including folders) there.
Thank you for idea!
ALM Works Team