Roman Neuhauser [off-list ref] writes:
... I like
my scripts as simple as possible, so I'd like to use --root *always*.
With "--root", the command does not do anything different without
for commits that are not root commits, and it shows "everything
created from nothing" for root commits. The option was invented to
help those who want that behaviour, so if you'd like to use it
always, then you are welcome to do so ;-)