Oh yeah, some mechanics need consistency.
It's when that consistency completely overrides the rest of the people who use a different form.
Annie's stun - reduceable. Fiddle's fear - reduceable. Warwick's suppress - misses if you blind or use Jax's E, and is interruptible.
Wukong, Malphite, Braum, Aatrox, Zac, Orianna, and plenty of others that I won't list because another topic has not only covered them but did so a couple weeks ago with a freaking Rioter admitting that yeah, knock-ups have an issue:
All unreduceable, all game changing due to the duration, all AoE. There are some that are single target (Hi, Vi), but those also have a tendency to screw over a team.
The worst part is that you're trying to defend it as NOT unbalanced when Riot's already said "Yeah, probably an issue due to the lack of counterplay. In that there is none besides don't get hit by the massive whirling monkey man who gains a freaking speed boost. Considering that these aren't lock-on abilities and can be avoided by dodging them in the proper manner, I suppose it's fair to say that you just have to not get hit.
Although that then exacerbates the problem that Brand, Syndra, Malzahar, Cass (kind of), Anivia, Karthus, Zyra (mid), Xerath, Vel'Koz, and still others (didn't name tanks because they get their bulk) have which is zero goddamn mobility in any way, shape or form, which turns being one of these champs into a game of "get them to blow their massive AoE ults so that I can actually do something - oh shit Vi's coming god damn it not again - dead". As Riot has said, they want to make sure each champ has a place (except Urgot because fuck that guy), but these kinds of actions continue to prove otherwise.
And if that weren't the half of it - there's not just one single lane where champs with these ults excel. Thanks to the wide variety (and variety is good, don't get me wrong), a team can basically stack knock-ups and win, baby, win. Again, zero counterplay, unless you want to say that instagibbing champions counts as "counterplay". But then Riot also said that instagibbing comes with zero counterplay itself, and have been taking actions to reduce that (hello Lichbane nerf, hello DFG nerf and following statement that they'd be working on a replacement). Meanwhile, the other mechanic with zero counterplay runs rampant.
Which then comes to the counterargument of "Well then just make sure they don't get a team like that". Which would involve banning all of these champs. Or picking at least most of them. Which, once again, eliminates that whole idea of "diversity". It puts several champs on a "danger" list and makes them take priority over everything else simply because they have one uncounterable factor.
So in the short speak: you were wrong the moment Riot said themselves that this was an issue. What I'd like to see is confirmation of either: A) if they're going to actually do anything about it or B) if they're just going to be like "yeah, that's certainly a problem" and then go bathe in their billions of dollars (I honestly don't know how they come out so clean when they bathe in nothing but money, but whatever, secret of the trade I 'spose).