It basically eliminates natural selection and makes the entire gene pool weaker. Anybody who learned about evolution knows about "survival of the fittest", which means that only the creatures with "beneficial" genes will survive to pass on their traits. Obviously, genetic diseases are not beneficial, and if we did not care for them, their disease would not be passed on.
NOTE- I do not believe that we should stop caring for them at all. That would be immoral, and I am against it. This is strictly a scientific poll.
In today's society, one with many disorders can somewhat function, and then reproduce, adding to the gene pool. They may then produce children with a gene for a certain disorder, but do not show the trait, and then they marry, and spread the gene. Natural selection occurs because the best fit are able to survive, and then reproduce, while the weak die. In today's society, we care for the weak and old, though they hold no benefit to society. Those with disorders won't die easily, like a zebra with retardation. They are able to reproduce, leading to future generations having more defects. Now, it is inhumane to let them die. I know that. But, it is agreeable that caring for the disabled makes the gene pool weaker. (Not as in crippled, but as in diseased)
Natural selection doesn't make the gene pool generally better. It just make the gene pool more adaptive. Now one research suggested that people who can't accept the world will make great things. If we don't care then all people would end up being the same conforming to society. Never trying new things. Innovation would drop. Also I haven't talked about caring them with genetic modification yet.