The new tanks and their 'niche' (and my problems with them)

Since the tank update was announced, Riot has declared that they want to separate and distinguish tanks from each other. Which is fair; a lot of them, particularly the initiation ones, and it's a good goal to have so that these champions have reasons to be picked other than "My CC is better" or "I'm better for this early/mid/late game meta" and more on "I fit this team comp really well, I should pick this" or "I can really throw a wrench into their team if I pick this." And we've seen the fruits of this new direction for tanks most recently with Galio, Amumu, and now we have the three that I'm gonna speculate on. So, in order of their updates, I'll assume I know what Riot wants for each of these renewed tanks;

Counter-pick to magic comps with his MR scaling. Strong peeling and good poke.

Amplifier to magic damage; presumably the highest synergy with AP hypercarries. (Didn't really change from before but it's more pronounced now, I'd say)

Using himself, his saplings, and his ult to occupy enormous amounts of space, possibly the heaviest zone control in the game?

Disruptor to the extreme, forcefully repositions enemies with Q and R, probably makes for a good kidnapper. (rip skarner)

a prank

My issue with these reworks is that their 'niche' or their supposed specialty takes a backseat to their very general strengths; crowd control. It's almost always just a minor part of their kit, or it just makes no sense with how the rest of them works. I can only speculate on the reworks as far as this go but I find it to be very noticeable on Galio, who feels like he wants to be a ton of different things; part of him feels like a tank, but he's also meant to be a fighter, but he's ALSO a poke mage. His 'anti-mage' shtick is just him stat-checking you with a lot of MR and a passive magic shield; the actual meat of his kit is far better suited for dealing with divers. He does a much better job at fending off a Xin Zhao than a Veigar; he just sort of survives the latter, without really doing anything special. And I think the same problem exists with Maokai, if you want to add more of an 'anti-caster' theme to him, too; nobody's gonna really care if all that happens is his passive just charges up a little bit faster around casters. He's still going to have 3 hard CCs between his Q, his W and his ult, and if those 3 hard CCs are good enough then he's still going to be a tank that fits into any comp, just like any tank with enough CC.

Before I start on Sejuani, I want to preface this with the fact that I am an avid fan of the champion, and a lot of this is incredibly reactionary speculation based on what we know, because I am particularly passionate about this project, I'll greatly appreciate any Rioter to ease my concerns on the subject. I understand that we probably know the least about her of the reworks, and I'll accept that I could be completely wrong and she'll become my favorite again, but I feel the need to vent about this anyway. Simply put; I hate how this new direction sounds, and I think it solves absolutely nothing that was actually wrong with her. Her high-impact ultimate wasn't a problem and I'm irritated that Riot thought it was. The real issue is that her standard kit has no interesting or remotely engaging play pattern. She jumps on you with Q if she needs to, presses W, she sits on you, and then she presses E off cooldown. There's very little counterplay beyond staying away from her, which becomes very hard when you account for her ranged stun ultimate and her fast dash.

The new E means that there's still not much counterplay, but now it's "avoid Sejuani and any melee champions that are close to her." What is the purpose of the melee-only interaction? Why is E restricted both to having at least one melee teammate and having him be competent enough to attack someone else so I can land multiple stuns? How reliant am I on this "melee teammate" thing? It's either you're going to be gimped without one, or it won't matter and the restriction shouldn't exist anyway. How does this play into her "heavy cavalry" shtick that Riot wanted to hone in on? I'm not seeing much reason to play her over anyone else with how the rework looks, especially if I have to play soloQ roulette and hope I get a team that'll pick something I can work with.

Zac.. is just great, honestly. I'm probably not going to play him, but this rework looks genuinely great. They didn't try to add anything new, no silly gimmicks or seemingly arbitrary restrictions, they just took what he already had in being the disruption king, and played it up in a way where a good player can be good with him. He is, at least until we see the reworks in full, my personal choice for the best rework of the three. My only concern is that now that his ult is potentially an AoE kidnapping, that Skarner is even more outclassed.

TL;DR Zac is great, Galio and Maokai need to have their niche things be more prominent, and I'm mad about Sejuani until I can play her for myself. Tanks in general should have more unique qualities.

Let me know how you feel about the tank reworks; do you think they're all great so far, do you think they could be better, do you hate them, etc.