The only real reason a Yasuo player should have any trouble with Xerath is if you can't dodge. Sure, he only has one ability (minus autos) that won't be deflected by wind wall, but that's his most damning ability. You just weren't playing the matchup correctly.
Besides, have you tried playing Xerath? You have no single target spells, and all of your spells have an obvious wind-up particle effect. Sometimes it can be near inescapable, but you run out of mana fast. Your passive does not give you enough mana to go spam happy, unless you land autos on the enemy champion (as opposed to minions) which defeats the purpose of having all that range if you're just going to go in close.
Also, if he's powerful in the early game, then be more careful and conservative, and when you get your power spike at level six, use you dash to get in close, use your knock up and ult him. He's remarkably fragile since they changed his passive from giving him tankiness with ability power to returning mana for autoattacking.
I personally think that people should play a champion before they say they need nerfed. I think Zed has one of the safest kits in the game, but I haven't played him so I won't complain about how he "needs a nerf." I don't know if he does, because I haven't faced the difficulty of learning his kit, however easy it is to pick him up and be good with him, as everyone claims.
If you have played Xerath and think he's unfair, wins too many games too easily, then I won't say anything to you about asking for him to be nerfed.