I really don't understand the Sejuani complaints
Yes she her jg clear might be weaker now with the changed E and W, but does that mean she's gonna be useless? God no. Hell she's not even out yet, and there are people are saying "omg rito you fucked up". Like have you played her in PBE? Have you gotten use to her abilities yet? Have you her played in JG yet? Have you played the new Sejuani in a lane yet? Stop complaining when YOU haven't played her. And when she's finally released, don't go into the boards and just say "she's shit now thanks riot", give actual good feed back.
And about her ultimate, Riot has literally stated when they confirmed Sejuani for the rework that they are balancing it out, so don't act surprised about that. Even if she can only stun 1 person, that big slow zone is still quite exceptional.
In other Sejuani thoughts, I feel like she's gonna be better in the top lane due to her E and W. That E does maximum health damage so it's gonna be great for trading and her passive as well.