Why doesn't "git flow feature pull" track?

Why doesn't "git flow feature pull" track?

Lets say I've created a new feature with git flow feature start FEATURENAME
then published it with git flow feature publish FEATURENAME
Now my colleague wants to collaborate on this feature with me, so he does
git flow feature pull FEATURENAME
This creates a new branch on his local repo, based on the feature branch
in the remote repo. This does not however set his local feature branch to
track the remote feature branch, so now he has to track this branch
manually.
What is the reasoning behind this extra step? Why not have the feature
pull command set to track as well?
What's the workflow difference between git flow feature pull and git flow
feature track.
In which cases would you use each of those?