Honestly, I can see it from both sides of thee discussion as I feed live crickets and mealworms to my reptiles and occasionally to my fish too and seeing them eat dose kind of make you feel happy, even proud knowing they are healthy and have a good appetite but its not seeing the cricket/mealworm get eaten, its seeing my animals eat.
Crickets and mealworms make up a part of their natural diet in the wild so its only natural and even beneficial for them to have the same diet if possible in captivity but, that said there are people who feed all sorts of live animals that are not naturally on the menu to their fish just for entertainment. That I have a problem with.
So to wrap this up before I end up writing a few pages lol, I've got no problem with feeding your stubborn carnivorous fish, live fish, its natural but if you can train them to eat pellets, why not do it? after all pellets are more nutritious or better yet, feed both, live fish and pellets.
Have a good weekend all.
Cheers-
Dazz