Why do you assume that the problem of a second-class existence for some is avoidable given the current state of the art in science, technology and medicine?
You can put wheelchair ramps on every building and have zero impact on the number of people that can walk that will date someone in a wheelchair, or the number of non-hearing-impaired people that will even be friends with a deaf person. This is because people often meet and relate to one another through their experiences and shared interests.
Frankly, the only way those situations can change is through technology. As we come up with ways of repairing spinal cord injuries, restoring hearing and sight, etc., many people will have ways of breaking through the very real barriers I'm speaking of here. Wouldn't it be better to spend more of the money that goes into ramps and the like on research instead?
If people are left free to decide what to do with their own resources, I argue that ultimately more resources will go into advancing science and technology, with the ultimate effect of creating a society where fewer people suffer a second-class existence. Take the existence of Neuralink as a practical example of this: it's a private company whose first users will be paraplegic people, and people suffering from strokes and Parkinson's disease.