Honestly, I don't see why ethics or morally have a whole lot to do with it unless you are causing suffering to other conscious beings. It seems to me more that people find it scary mostly because they cannot really comprehend it.
I am lucky to work with people in the space sector who are studying this on a daily basis. Our wish is to master the genome as "easily" as mastering computer code. So that if future astronauts are exposed to an environmental challenge where their human biology needs to adopt, we can simply understand the phenomenon from Earth, measure what biological changes they'll need to survive in the environment they are in, and upload the genetic changes as code. Sent with the speed of light from Earth, to computers on other planets that then make changes to the bodies of astronauts.
Seems far fetched? Well it is being worked on :)
Anyways I think with all the flaws nature has afflicted upon life, to begin with, it is only moral and sound that we make the necessary changes that allow for human beings to flourish more and suffer less.
Maybe I'll have to cover the topic of space biology in one of my future blog posts, having only yesterday posted my introduction post on steemit I'll be looking for more topics that people find interesting related to space and science :)
I agree, the line to divide what's right or wrong seems to be always very thin. Let's look at AI for instance. As a software developer my job has always been to create applications to automate tasks even where my own intervention is required. So now AI is creating excitement and concern. We are fascinated by the idea that a machine can learn, but worry that the same might turn against us. If the gods who created us had known how we would have turned up would they had stopped creating us?