Current Situtaion

The current option (deleting all groups and manually add one by one + adding these to users again) is a an hassle, because you need to know what groups an user had. And lastly, you need to reconfigure permissions again.

How It Works?

When Re-arrange Groups mode is enable, you can change the order of groups without needing for doing the steps stated above.

Why It Will Be Useful?

This feature should be useful if you want to arrange your groups nicely without the need to do the nuke-add-adjust-add people method ever again.

I suppose you're referring to the order the badges show on a user profile?

Or also the way they appear in the permission dropdowns?

I'm not sure whether it's currently just ordered by ID or by name? I assume the current system was made with just one group per user in mind.

It does sound like something we might want to add to Flarum core at some point.

3 years later

Finally, was this feature implemented? I couldn't find it. As @ajhalili2006, I've also created some new groups in my forum that I'd need to appear at the beggining of the groups list. Ideally, I'd like to have them reordered everywhere, but at least, it would be enough if I could change the order of the badges without having to delete/rebuild/reassign all the groups.