I have some sympathy with the deaf couple who wanted to choose to have a deaf baby. People do not have a positive moral right to make such a choice. However, I think that it would be morally permissible and that it should be legally permissible to do so. It is wrong to deafen a child who would otherwise have been able to hear. It is not wrong to choose to have a deaf baby who otherwise would not have been born.
I have some sympathy with the deaf couple who wanted to choose to have a deaf baby. People do not have a positive moral right to make such a choice. However, I think that it would be morally permissible and that it should be legally permissible to do so.