why not even to the products, like honey, milk or eggs?
exploitation of animals, insects, egg layers.
Look up what is done to calves to ensure a good milk production from cow's. The antibiotics and hormones routinely fed to cows to keep them milking longer. What happens to cows when they no longer produce enough milk to be economical? Dairy cows are not eaten by humans when they are killed. That is 'beef' cows only. Cows have a natural age of 25 years. Dairy cows that are solely for milking are usually slaughtered at 4-5 years old because they no longer produce enough milk (not a case of not producing any milk) to be worthwhile keeping.
Hens don't fair much better. their natural lifespan is around 7-10 years, yet they only lay eggs for 2-3 years at best. if they don't lay enough eggs.... and they are usually killed at around 15 months old when they no longer produce enough eggs. the conditions the are kept in can often be less than ideal. Free range is not always free range and battery eggs are exactly that - a caged hen for all of its life and that is only the female chickens. Males are killed when they are 2-3 days old and then fed into the various food chains for dogs, cats, snakes or their bodies just burnt. Male chicks are not considered suitable for human eating purposes. Female chickens only for that and they are selectively breed to grow really fast and are usually killed when they are 5-6 weeks old! And sadly free range does not always mean free range as in outside able to feed naturally and roam freely - it simply means that they are not caged. they can still be in very crowded, unsanitary conditions (hence routinely fed antibiotics) and often not even in the open air. Free range often means in large sheds of upto 16,000 birds at any one time! I could go on about debeaking and aggressive behaviour at egg laying time... but I won't, it is too depressing.
Mass production of honey is another issue entirely. Honey is removed way too often to support the hives naturally.
Insects are bred in their millions to produce food and clothing dyes, their secretions are used for glossy coatings of sweets, you know that polished crunchy look some sweets have? Shellac...
Silk moths are boiled alive to obtain the individual strands of silk because it is the only way of unravelling it without it breaking.
As for the plucking of down from live birds such as the eider...
Rabbits don't fair any better - angora rabbits are pluck alive repeatedly for their fur to make angora wool. It makes them bleed....
Those are just the moral reasons.
Health wise - humans never evolved to consume milk based products from any source other than humans and only for a certain age span, It is one of the reasons many people have an intolerance to lactose and some of us an allergy to all dairy.
