Nature is pretty damn cruel and selfish at times. Just because it utterly sucks doesn't mean it isn't natural - similarly healthy has the question of healthy for who and when?
Illness in herd animals is healthy for wolves by making them easier to kill without injury.
The industrial revolution saw major growing pains and destitution but raised standards of living greatly.
Your somewhat patronizing analogy misses the point. If our ultimate goal as a species is to survive and live well, then cutting hundreds of thousands (millions, actually, if you think about the implications of automation in other areas) is in conflict with that goal, thus 'unnatural'.
If the goal is to live well, that has nothing to do with doing jobs that a machine can do. Automation is not in conflict with the goal of people living well. If anything, it's the best tool we have to achieve the goal.
The conflict with the goal of people living well is that we don't want to take wealth from those that have it and give it to those that don't, without making the ones that don't have wealth "earn it".
Otherwise, there is nothing stopping societies from gathering up all the extra profits from automation, and using it to invest in education, healthcare, reducing number of work hours, increasing vacation time, i.e. living well. But we would rather not have that.
I agree that automation should be (and many times do) helping people perform their jobs (and daily tasks). However, those who are 'in charge' financially are actively seeking ways to replace humans in a blind race for maximizing short term results.
In a 'healthy' society, automation should be employed to make humans work less hours and with less risks. Somehow many people think this statement is absurd.
The solution to this are labor laws that result in less work hours for everyone, that apply to all employers. A universal basic income would also help accomplish this. The problem then, however, becomes how do you compete with another country that does offer cheaper labor.
The purpose of work is to do something useful as well. Makework is even more unnatural which is what automatable jobs being kept for the sake of employment only are. That level of waste mounting isn't good for living well as it calls for what is essentially wasted resources and lifetimes.
The true issue is adaptability or lack of it in an economy. The replaced should be doing something actually useful but that process is less than straightforward.
Illness in herd animals is healthy for wolves by making them easier to kill without injury.
The industrial revolution saw major growing pains and destitution but raised standards of living greatly.