Toddler Stuff Pack looks lazy...

I think what makes it look really bad isn't the low number of balls, but the surface of the pit. It just looks both flat and distorted. That's why the spaghetti pit looks better; the stretching and distortion isn't so obvious.

I expect that now, they wish they HAD done a paddling pool or a sandpit. But they thought, "We've never had a ball-pit before', and it probably looked much better in concept art. So they did the stat reactions, and then the animations, and then, whoops.