While I agree about this being cruel and should'nt be done, I find we are all hypocrites as to what WE feel deserves to live or die in out tanks and how they should be treated.
You never hear people bringing up the cruelty to feeder goldfish, yes, you do hear of the dangers of introducing them to our tanks due to disease and such, but I have yet to read one post of their treatment. How many of us don't think twice of flushing pests that make there way into our tanks for just trying to survive such as crabs, snails, nudibranchs, anemonies, hydroids and such.
I did'nt make this post to point fingers as I too am guilty of such practices, I had a Gorilla Crab taking down some of my Zoanthids a while back, my plan was to catch him and keep him in my fuge, after about 2 weeks of him alluding me I was at the point if I could just spear him to get him out of the tank I would be happy. After I thought about it, it boiled down to me not wanting to lose money on corals in my tank, not the fact that this creature was taken from it's natural environment, only to wind up in my tank where I was the one who gets to play God and decides who deserves to live or die, based on how pretty they are.
We all claim to be animal lovers, but really who are we kidding? Do we keep these animals to help keep them from extinction or anything helpful? No we simply do it because we are at the top of the foodchain and can do it for nothing more than our own enjoyment. Myself included.