Maybe they should just remove knockback, huh?!...Yeah...no.
Honestly, casters are the only ones that can reliably negate knockbacks. Surecast have only 30sec cooldown and 5sec up-time. Paladins skill have 180sec cooldown and 10sec up-time. The skill is so weak in comparison, that I would honestly prefer it to be changed into something entirely different because of that insane cooldown. In terms of melee, it's still 60sec for 5sec up-time, but at least have slow effect added (which won't really matter against bosses).
In case of melee and casters, anti-knockback evens out the odds a little bit against the ranged. Melee don't have to waste time on movement while casters don't waste their spells in the middle of the cast. Ranged, simply speaking, are scarcely affected. Generally it's nothing that positioning (which costs them nothing) can't solve.
Classes are supposed to have strengths and weaknesses based entirely on their role. Casters have the glaring weakness of cast times. Melee the weakness of having to be near. And ranged?!...Eh...yeah?! Right...And you want to remove the slightest semblance of weakness...I'm not talking here about the stats or potency of the skills, I'm talking about the core gameplay. Ranged have NO weaknesses. They can attack from up close and at range. They can attack while moving. They can stay away from dangerous cleaves and swipes of bosses without being affected by it, and the closest they ever need to get is about 20 yalms away from the tank, to be sure that they will be caught by Medica and similar even if the healer is overly fond of stacking almost on top of the tank to keep him in range...
If you want to remove weaknesses, small or large, make the suggestion while adding new ones. Or, hey...A bow-mage is still an option. Then, by all means, go ahead and ask for a sure-cast grade of anti-knockback.