It has nothing to do with fairness, its just a dumb ability.
If Riot actually added more champions that could ward jump it would be a perfectly fair mechanic, but it would still be a dumb nonsense ability to have.
It makes no sense for most abilities to be able to jump to wards. Look at Jax, his ward jump is an ability that is supposed to be offensive in nature, jumping on an enemy and hitting them, so why can he jump on a ward or even his allies? Look at Lee Sin, his ward jump is a ability to come to the aid of allies, so why would/can he jump to a ward?
I have no doubt that when these kinds of champions eventually get reworded, they'll get their silly ward jumping removed and replaced with properly functioning abilities that make sense. You can already see it happen when Braum got released, he didn't have a ward jump even though his ability is no different from Lee Sin's. They probably aren't removing existing ward jumps just yet because it would fuck too much with the kit and power balance of the champions.
At least, I hope they'll remove this nonsense eventually.