[ElevenLathe]

I can imagine de-extinction and other genetic engineering techniques being useful to increase the amount of diversity in many habitats, which will theoretically give them a better chance of weathering huge environmental changes (as natural selection has a broader base of genes to work against). Since we need the biosphere to continue existing in a pretty narrow range of configurations in order to keep us alive (for example, we probably don't have the technology yet to sustain our civilization in the face of the whole planet becoming a desert, or not providing enough oxygen to breathe without artificial assistance), this might be a useful technique.