I raise all my own feeders (primarily convict cichlids and marbled crayfish), I don't feel bad for them though...I maintain their tanks the same way I do all my display tanks and treat them with the same respect as I do my other fishes. I love to watch my aro's, oscars and catfish go after them!
Having said that, I do feel bad for the feeder fishes at most pet stores...each getting 1 sq cm each of tank space, disease running rampant, horribly underfed, etc, etc....I don't feel bad for them being feeders, I feel bad because I respect life and think they should be treated with respect.
Case in point, when I buy crickets for my green anole and fire belly toads, I put them in an aquarium just for them, with proper heat, light, hiding areas, water and food in order to promote healthy traits in them before moving them to my terrarium. I rarely have more than 1 or 2 die out of 50 before feeding them to the lizard/toads.