That’s the point, in camis or fatigues, a Marine can look just as sloppy as an Air Force Airman (okay, maybe not quite as sloppy unless he slept in his clothes for a week).
This is not something new, it goes with Marine tradition to not only be the proud , the few, but to look it too.
I can see urging them to wear a dress uniform off base but not requiring it for a quick stop at burger-doodle.
If a solider is active duty they should look like it IMHO and that would include any issued uniform suitable for the occasion.
BDU’s should be fine for Walmart and burger doodle.