The workspace needs a more permanent architecture planning section. The Draw.io functions within notes section are very helpful but are attached to features and releases, which tend to be transient in nature. An architecture workspace would be more permanent and evolutionary over time.
Thank you for your idea. Currently, mockups and files can be attached directly to products from the Products > Overview screen. These mockups can be easily added to Notebooks and they also appear in the Product > Files section. This would be a great location to store architecture planning diagrams and mockups.
Given the capability above, we are unlikely to implement this idea. We hope you can understand.