Things I don't understand why some Champion have that kind of utility in their kits...

: Why for the Love of GOD does her Q slow? So she can easely hits her skillshots?

: Why The heck does her Ult slows? She has shieldbreaks on it already does it really needs to slow? How am I suppose to escape her ult? Walk fowards, thats clearly the option to go. And why does my own lane minions are playing against me? Do they have some sort of a.i and align themself soo Irelia can gap close easier?

What would happen if you remove the slows of these 2 champions? All I can think off is 2 scenarios,

Either the champions they are trying to kill have more survivability chance against them

Or

All their match up are slightly harder and they would have actual counterpicks.