leading and army into battle doesnt necessarily mean leading them from the front lines.
That might be relevant if we weren't taking about Sejuani. Sej is a frontline leader, she always has been, she is if you read her lore and it's pretty clear that when Riot said leader they were aiming for frontline leader.
i'd disagree with her feeling underpowered and unsatisfying.
Unsatisfying isn't the same as underpowered. Cho'gath's also often pretty unsatisfying to play too and he's a straight up broken piece of shit. Right now I think Sej is slightly too powerful, but still unsatisfying.
she's got her flail skill shot that stacks a single stack for her E, but knocks away minions. use it incorrectly and you'll end up adjusting the creeps in an unfavorable way.
Sejuani's W always stacks creeps. The only way it can be negative for you is if you stack creeps on top of eachother and their clickboxes stop you from clicking the creep you want, this can be fixed by moving 2 steps back so the creeps have to follow and unstack, or if you don't feel like moving you can also zoom the camera in and edge click the target you want to AA. VS lane creeps you can target stacked creeps anyway, as you move your mouse over the creeps HP bars will move backwards and forwards, you're targeting the one at the front.
she's got a passive that grants her added armor, magic resist, and slow resist. if a player gets too reliant on that added protection they can forget to maximize their loadout, fail to engage effectively and become unaware of their own potential in combat which leads to feeding more than assisting.
I don't even understand what your argument is here, you're accidentally arguing against your own point. Sej before was just less tanky, you had to play around being less tanky. That takes more skill. New Sej has the durability buffer which can often save her when she mispositions.
her dash is her only means of escape.
Yes? It also was before her rework, what's your point?
but with her frost armor it can be used to escape.
But that's reducing skill cap, it's saying "you have to do less to survive until your second Q". That's unarguably making her a lower skill champion at least when it comes to surviving/escaping.
her R is a skill shot that is easy to waste when used against mobile champs.
I've seen a Lucian dash almost sideways and still be hit by an R at close to max range. The hitbox on R at max range has a diameter of 250 units or so, it's actually fucking giant. Given the speed and the size of the projectile it's hard even for mobile champions to dodge, the old R was slightly slower, far smaller and considerably more worthless when missed.
E has to be up in order to capitalize on your R.
This is completely wrong and shows a fundamental misunderstanding of Sejuani as a champion. Sejuani cannot stun a champion who was stunned by her R with her E. You actually use E first because of this.
choosing to play sejuani when no one on your team can melee attack is foolish. there's a lot of skill involved in simply knowing when to choose to play sejuani. for example jinx, lucian, yi, graves etc. on the other team? dont bring sejuani. they'll just power through. got a tryndamere, a yi, warwick, or xin zhao on your team?
That has nothing to do with skill. It's purely game knowledge.
that E effect makes a huge difference based on your composition and the enemies composition. so i'd argue that it's one of the MOST reliant on skill - even if in a match it's a simple point and click damage chunk.
The E isn't particularly skill reliant because there's a potential for Sejuani to fuck up everything and still impact because of it. You could wiff your Q, miss W completely, throw R backwards and just have your Irelia AA a few times then E-AA and still have a huge impact. That's the definition of what makes something low skill, to me at least.