I think it would be if they added other champions sheathing or putting away their weapons when out of combat like 
.
and 
already retract their blades during emotes, why not out of combat too?
, 
, 
, 
, and maybe a few more could put their weapon on their back, hip or sheath/retract it. I think it would add a little bit aesthetically.
Uh....Talon's katar is basically attached to his hand. Why would he take it off his hand if he's supposed to be prepared to fight at all times? The same goes for Zed, Nocturne, Darius, Riven, and Wukong.
The reason Yasuo sheaths his sword is because of something called Iaido, which you can read about here: http://en.wikipedia.org/wiki/Iaido . Also battodo. Essentially, it is a katana technique used by samurai to make an attack directly from the sheath'd position. So really Yasuo is not putting his weapon away to relax--he's preparing to attack again; notice he doesn't take his right hand off the hilt, or his left hand off the sheath. It's because he's ready to strike at any moment.
So I don't think having other champs put away their weapons is a good idea, because they're on the fields of justice: they should be prepared to attack at every moment. Yasuo sheathing his sword is just his way of preparing for battle.
