It's easy to tell humans that they are amazing angels and gods, who have every right to transform all other life, and the planet itself, into whatever humans believe will benefit humans. Such "rationale" is what makes Libertarianism and biotech utopias so easy to sell-- they appeal to selfishness, cravings, and greed that plagues many people.
The fact is, humans have godlike powers and they use them in a mad rush to consume the entire planet trying to build a perfect world that benefits humans.
In converting sun energy, other organisms, and the earth itself into the human culture project, humans decrease biodiversity, create unintended negative consequences, and harm humans and other organisms.
Biotech is an industry and like all industries, it's all about money and power. The human re-engineering of the earth will benefit some people for a while. In the end, it will create a dead, mutant planet.