Yes I would say its necessary. When shrimp molt, they hide until their carapace hardens again. Java moss is the best place for shrimp the hide. When the fry molt, they hide in the java moss so the adults dont eat them.
Necessary? I agree with most people and say no, but it's such an easy to care for plant that I would go for it. I have a huge ball in my Dwarf Crayfish tank. They climb all over it and it helps with the bioload. Plus it gives a little shielding from the light.
yea I like the look of it but geez it floats everywhere. I have it tied down with cotton thread but the fly aways are annoying, I keep picking them out of my tank lol.