I honestly think people have the freedom to do whatever the hell they want for the sake of their happiness, as long as it doesn't harm others.
It's a given that genes that lower a species' rate of survival are bad for said species' gene pool, thus bad for the species as a whole; but the damage retarded people cause to the human gene pool is too marginal for us to even have this discussion.
Additionally, it's not like retarded genes are expressed in a substantially large percentage of current living humans to be detrimental to our society and population. If it doesn't need to be fixed, why should we fix it? Better yet, if it isn't a problem, why does it need to be addressed?
EDIT: I think the real problem that needs to be addressed is: