It's not disgusting. It's a question of how we view nature. The idea that we can just preserve ecosystems as they were isn't very tenable. The idea that invasive species don't deserve to be invasive is questionable. We're making all these value judgements about what nature and shouldn't be. But nature has always changed, just depends on the time scale.

And life has always spread into new areas and become invasive. We did so migrating out of Africa. So does an ant colony floating on a log to an island that didn't have ants before. Life colonized the oceans, then it colonized the lands, and it colonizes new islands that popup, and populations shift around as the climate changes and new migration routes become available. The Sahara was a savanna thousands of years ago.