Orgin purpose of this shell is big "F*ck you" while ISU get a wrong shell type. Or you could use it as big money shot.
Sound good on paper but in reality it was a mess. Hard to hit moving target, even brouncing, pen heavy tank. Shoting defendsive position also miss, overshot too.
I guess because the mechanic of dual purpose shell and skill click abiity itself.
If it could change to vector ability like Tulip Rocket/HVAP M26. It could be fine. Let it hit, kill everything on it path.
The shot has very little to no scatter and will land where it aimed.
Changing it to vector ability would be a bad idea since the unit has no turret and has to rotate without adding much since it can still collide with target in its path.