Much as red ties and huge flag lapel pins are de rigeur during the Republican primary, suits are not the only garb.
There are days when candidates wear jeans, if they could carry them off. (Romney apparently thought he could carry off mom jeans because he donned them often, but he was mistaken.) Suits also get dumped if we have bad weather.
Indoors, those who govern us by our consent (theoretically) will, for example, wear a sweater during a snow storm.
And, when they wish to show solidarity of some sort, they dress similarly.
Raise you hand if you think either the clothing or the body language and serious to grim facial expressions in this photo, for example, were merely coincidental:

If they weren't coincidental, then someone actually spent time on this kind of thing during a crisis in an attempt to send us a subliminal message. And, imo, we should not like either the expenditure of time nor the attempt to affect us without our realizing it.
Btw, Obama's wearing his Air Force 1 jacket to tour disaster areas, while theoretically suspending his campaign for the Presidency, was no accident. (Neither was this photo.)