But doesn't kin selection explain only tribal cooperation, not moral empathy towards perfect strangers?

Yeah, the extended phenotype idea is interesting. But again, our species has taken this to another level. Modifying the environment is one thing. Growing artificial society at a cancerous rate at the cost of potentially ending all life is another. There's an existential dimension to our anti-wilderness behaviour that I'm trying to explain.

Did the antelope vanish as we switched to farming? The transition was progressive in that it eventually supported our population explosion. But I agree that we might be only rationalizing causes after the fact. There's what we intend to do, and then there are all the factors that go into explaining why events happen as they do. Our intentions emphasize some factors and ignore others. The total cause always outstrips our imagination.