That is linear neo-Darwinian thinking, and does not reflect the messiness of life. In this discussion, nothing has emerged to fill the niche vacated by the Parakeets:
Carolina Parakeet; are non-native parakeets filling this niche? - Nature Talk - iNaturalist Community Forum
In reality, humans have no idea what will happen if species go extinct. If the clearing of rainforests stops today, and the agricultural land left alone, what would re-inhabit that land?
While I can see your points, I do not think humans have to moral right to destroy habitats and biodiversity just because we want big houses with pools and nice big lawns. Especially since we have a chance to halt and regroup. Especially in the rich world - the environmental impact of a subsistence farm in a poor nation is minimal compared to the acquisitive consumption in rich nations.
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