I don't know, it looks so weird, having Gangplank's crew who has gotten A++ in their Mathematics to fire cannonballs at such a proper circle AoE area. Why not make the cannonballs' design to look just like the old GP ult, but keep the new damage as it is. More pref this way.
Presumably because keeping the old visual effect would fail to communicate the change to the way that the ultimate functions, leading to players complaining that they were still taking damage despite visually dodging the cannonballs. The point is to represent that it's a consistent per-second tic of damage rather than something random and per-shot as it was previously.
I agree that it doesn't look or sound anywhere near as good, but it's a matter of visual clarity.
