Giving it more height and vertical movement, while very beneficial, may not be enough to compensate. Both side B and Down B cover a lot of the distance, and stretching Up B to go such high distances, especially horizontal, is very absurd for the animation. You'd still only have one move to use anyway, which certainly removes any unpredictability, unless you're able to really swerve a lot while doing, which again would look absurd. A new up b might work, but I kinda like the current one.
I do think it would be cool though if Side B was switched to RIDING the Poltergust like was just suggested, as that would still keep the recovery aspect while possibly bringing in more onstage utility.