There is a train of thought that caring about animals will help solve human problems. When society values life, and children are taught that killing is wrong, this has a great social impact.
Soldiers who have killed or committed genocide, for example SS guards at Nazi concentration camps, often reported thinking of their victims as "just animals." Historically, "black" people were thought to be a different species to "white" people, and therefore no better than animals - hence they were enslaved.
It is thought amoung the macrobiotic community (and I have to confess that I don't know of any hard scientific evidence for this) that eating meat makes people more aggressive and violent.
Social problems
have been linked to increased consumption of hydrogenated fats in underpriviledges areas, and there is an established link between certain preservatives and behavioural disorders in children. Whilst these are not a direct result of eating meat and dairy, they
are a result of eating processed food, which tends to be non-vegan.
Of course, we should remember that Hitler was vegetarian...
In any case, eating vegan/vegetarian is a relatively easy, small step to take on the path to solving the rest of the world's problems
