The funny thing is, is leaving the land "the way it would have been if left alone" better? In many cases, it is debatable.

In New Zealand, there are many invasive species of animals and trees. Should they interfere and try to remove the invasive species? Or you should they "leave it alone" and let the pine trees take over all native plant species? (the same is happening in the french Alpes where pine trees are invading a lot of land).