The luck of the draw, I guess. I've got a pair of krill lights that still work after maybe ten years of use at Burning Man.
Krill lights are still made:
http://www.kriana.com/pages/howtochoose.htmlbut you wouldn't want to throw them away.
Tossing cyalumes into caves and ponds seems not to be a 'leave no trace' event. Different strokes for different folks, I guess. You'd think we've got enough trash on the ground without throwing more into the caves.
WHERE did I mention that items were LEFT??? Just where.
Maybe it's me but I would rather get a non-battery powered device soaked in water, mud, dirt, and nasties than a battery powered one that could go out, get ruined, etc.
AND on the chance you forget it or "leave it behind" you are not out more than 75 cents.