I think the quiet option should just be accomplished by guarding the output under if self.verbosity > 0:, like we do in other commands.
We might want a tree structure at verbosity >= 2, and Sarah’s concern about length could be worked around that way (authors of fat templates wouldn’t recommend using -v2 in their tutorials, whereas authors of skinny templates might).
I agree with Thibaud’s view in the ticket that the tree could be follow-on work. We could merge a PR first with the one-liner success message (possibly with the additional suggestion here).
What if the message was defined as part of the template, in a file like .success or similar.
Nifty. Factoring out the message into a class variable would be a Django-idiomatic way for an installed app to override these commands simply.