Why do the mechanics of Gangplank's ult have to be tied to its visuals?

Before it was updated to be more consistent the damage and slow only applied if you actually got hit by the cannonballs. The fix was, instead of just making the damage and slow proc regardless of where the cannonballs landed (such as with Anivia's ult), to just make sure you actually got hit by the cannon balls by having them all fall at once, which is quite a bit less satisfying than the previous animation. I honestly don't see why it couldn't have just been changed to have the damage and slow to apply to anyone in the AOE without them needing to actually be hit by the cannon balls.