When I was a little boy... all I loved were Final Fantasy Dragoons.
Make Xin's E a skillshot. A skillshot with a small aoe and a slightly longer range. Make him jump in to the air and plunge attack hapless foes on the ground, because it actually seems way more aggro than his dash. It has way more skill expression than his current E while also not really detracting from it's reliability. Yes it can be outplayed, but honestly his current dash has an extreme level of outplayability because he will always dash to the side of you he's already on and it's very predictable.
Letting him choose where he lands after a 0.5 second period would let Xin make plays. His kit honestly has the potential for it. Look at his ult.
And you'll fulfill a young me's desire to play a god damn Dragoon in a non-turn based RPG.
Is this selfish? Not at all. I genuinely think the change would help him, I'm just playing the Dragoon card because ever since I saw Dragonslayer Xin I felt like he could be League's Dragoon.