It's so obvious why someone would pick other Duelist Agents before Yoru. With Jett and Reyna you can hold an unsafe angle/position and then instantly Dash/Dismiss away when you're in danger. Then you have Raze and Phoenix, who are able to provide utility to the team while holding a position and make the enemy stay back. It's so fun because these agents give you tools to apply pressure and be aggressive even in Defense instead of just sitting in a common position like other agents.

Yoru has no team utility so he's in the same category as Reyna/Jett. Bad news: You can be as aggresive as them cause even Raze's Rocket can kill you before you teleport away if she's close.

If Rito doesn't nerf the Dash/Dismiss, they SHOULD make Yoru's teleport instant so he is invulnerable the moment you press the ability, to be able to compete with these two ladies. (It would be interesting 10 more seconds to the teleport duration tho, but not sure)