... But we are talking about Trees, not tigers. They don't "feel" anything. If they look good and healthy, it means they are good and healthy... because that's all they are.
Comparisons to other human activity are only going to make it seem comparatively innocuous and there's a gulf of difference between the relative and the absolute.
[1] honestly the alive/not alive bit isn't even strictly that important. People are often fairly opposed to destroying various rock features, even when it's for the purpose of a very practical and utilitarian dam. Somethings resonate with people in a way that they want that something to be allowed to just be
So the difference is purely about aesthetics, which brings us back to why people do bonsai...
Though it's worth pointing that most people care about the difference between killing something and controlling every aspect of that things life.
I read your full comment, and I don't really care what you care about, my point was to point out that your point was inconsistent, whether you were expressing it as your "own" point of view or a "friend of a friends" I don't care, the point is still inconsistent.