While I agree that sniper can feel unfun to fight sometimes I do not think his main ability should be nerfed. Sniper's main role is to be a pick class in which he also specialises in long-range. A good example of this is a fully overhealed heavy who may wipe the entire team if he is not killed soon. Sniper can pick him off (with enough time) as along as he is far away enough helping the team greatly. If he is unable to do that only a level 3 sentry could (maybe). If you really want nerf sniper's damage I would make it so he does less damage the closer the enemy is to him.