Because they’re awful for what they are. They’re barely good as glow sticks.
Very low diffused light, needs bright lights to recharge, preferably UV. Most importantly, the brightness is brief and doesn’t last.
As a kid I remember loving GITD anything, but the disappointment was always the same.
I mean if that’s what you like, and they specifically ask you what you want on it… I’m sure subway employees have put together far worse science projects than that.