Is the gap between rich and poor really so important that we should refrain from curing diseases to avoid making it larger?
Making a rich child immune to diabetes or autism doesn't hurt poor people. It's strictly a net gain.
What's fundamentally different between this and, say, prenatal vitamins or good nutrition? Should we ban women from taking folic acid because it gives an advantage to people who can afford it?
Let's say an in-vitro preventive for diabetes could be developed but is blocked because of concerns about gene editing. That means thousands or millions of children will contract diabetes who wouldn't have if the preventive had been available and will die prematurely. How is that a good thing?
I can sort of buy the arguments for purely cosmetic changes like selecting sex or eye color or whatever. I can vaguely grasp the arguments against selective intelligence or physical strength enhancement. But to refuse to prevent diseases? Why?