The only truly ethical diet is to only eat fallen fruit. I don't see how raising and killing living organisms, whether plant or animal, is ethical. The difference between a cattle feedlot, an industrial chicken coop, and Foie Gras is splitting hairs, IMO.
I have no problem killing and eating animals, but I don't think it's the "right" thing to do. I think it's neutral at best, or acceptably malevolent at worst.
Believe me when I say I'm a dedicated omnivore. When you spend 18+ years on a livestock farm you become pretty immune to doing tasks which some people see as "wrong". I guess my only point is that animals are not the unthinking, stupid things with no feelings that some in this world think they are. We never did things to animals "just 'cuz" and I don't think that is what farmers who raise geese for Foie Gras do either. We did what was needed to keep our (and your) food healthy and did our best to make as non-painful as we could. I just don't think I could have force fed a bird like that. Others can and people appreciate it. I'm not judging, just admitting my limits.