I'm asking to reconsider the following limitation:

Default space templates differ from ordinary page templates in that they do not present the user with a form to complete, so variables should be limited to those listed above.

(Source - Customising Default Space Content)

It feels like a pretty serious limitation to me. If custom fields can be prompted when creating a new page within a space, why can't there be custom fields when creating a new space? I'd argue that sometimes it's even more useful. Because every space is usually attached to a project, it makes sense to speed up project bootstrapping by providing coworkers with a form that requests things like:

• Project URL (e.g. test server, production server, etc.)
• Brief project description
• JIRA URL (though it's a shame I have to manually assign links between JIRA and Confluence every time, jumping between the two within the same project should be easier)

And use that information to generate a more useful space homepage.
This would obviously be faster than first creating a homepage with default contents, hitting edit and inserting information into appropriate places inside the page (which can be long).

But besides speed considerations, it would also be a mechanism to require people fill out some minimal project information when starting. That is important too.