This question is a broad one, so I will address one specific moral and ethical issue in detail. By writing Never Let Me Go, Ishiguro insists that the reader confront the tension that exists around the normalization of artificiality in today's society. This is a moral and ethical issue for many people, as things that are artificial are being mistaken for real, which causes problems of trust and reliability.
Artificial is a synonym for fake, or created, or contrived, and it is the opposite of words like authentic, real, and natural. The artificiality of the clones and their creation for the purpose of harvesting organs to save humans are a reminder to readers of all the artificiality we have come to rely on in our own world.
Any teenager can identify any number of day-to-day artificial experiences, ranging from "friends" and relationships on Facebook that only exist on the screen but somehow hold emotional power, to so-called "fake news" that misleads society and rattles faith in journalism, or to artificial depictions of life supported by social media that mislead viewers to believe they are true. Though Facebook, the news, and social media all have positive qualities to offer society, the artificial side of these important social influences can be dangerous, much like the cloning of humans for human benefit is morally dangerous.