For a bit more complex projects like I have, management of spaces and databases becomes an a bit of a challenge. I currently have a space with 40 databases and entity types with 20 fields, and growing. The reason for adding all databased together is that mangement of them is a bit easier, and to reduce the amount of spaces in the left column.
With a big database of many fields, the table becomes very wide with many columns, and having overview of all fields is difficult, one needs to scroll horizontally a lot.
What I can imagine is a central databases management dashboard that shows all databases in the workspace, of all spaces, that allows easy adding of removing of fields.