You have to remember that in the "natural world" (whatever that means), trees are damaged all the time by browsing animals, falling limbs of older trees, intens

You have to remember that in the "natural world" (whatever that means), trees are damaged all the time by browsing animals, falling limbs of older trees, intense weather, falling rocks, etc. They and their ancestors have evolved under variations on those conditions for millions of years, and as such a lack of those things in a controlled garden or suburban environment is an unnatural way of growth. Our (imperfect) knowledge and judgement can allow us to, rather than provide an environment totally lacking those natural events, wisely prune trees in ways which help them grow stronger than they otherwise would. Although you may intuitively feel a certain way, feelings are sometimes wrong.