[scarmig]

I agree with your last sentence, but:

Any particular bit of code is a visible element in a much larger system that is horribly complicated, and which no one fully understands.

The issue with hacking human embryos is that it's like working on a four billion year old legacy code base, written by toddlers smashing keys on a keyboard, in a language with no abstraction and where all variables are globally scoped. And the only testing you can do is to watch embryos die quickly or develop into people to die new and uniquely grisly deaths.