What are best practices for the Space Creation policy in large companies?

Hi,

I'm administrating an instance of Confluence in a a large company (>10,000 employees).  At present, the policy for creating a space is to send an email to one of the Confluence admins where it gets manually created.  In general, this is just a rubber stamp so I've thought about creating a self-service kiosk or creating a space.  Which to me begs the question why I wouldn't just give general users the permission to create a space in Confluence.

So I'm wondering - what policies/practices to other users follow?  Are there reasons to restrict space creation to a few admins?  Are there companies who use self-service kiosk models, such as with Bob Swift's CLI - and if so why use the Kiosk rather than allow users to create spaces directly?