I asked a friend of mine who's a Sci-fi enthusiast. He said ' I think SF creators have the unspoken idea that there will be no such thing "in the future"...'
The author of the linked article addresses that: "Contrary to ableist opinion, a utopia is not a world where disability is a problem that’s been solved; rather, it’s an inevitable expression of genetic variance, and disabled humans are not just welcomed but fully included."
I showed that to my friend and he didn't really respond to it. I was kind of hoping to get more from him on the subject but he seems reluctant to explore it.
The truth is, most people don't have close contact with people who have disabilities. It's not something we deal with or think about on a daily basis so I suspect that an author who's not close to anyone disabled isn't likely to ponder how a disabled character might fit into a story.
I think if one did ponder it they might find some very interesting avenues to follow, and if this opinion piece sparks some thought along those lines that's a good thing. But my attempt to discuss it with my buddy didn't reveal much curiosity for exploring it.
Hardcode sci-fi fans tend to view opinions by casual consumers of the genre (like me) as an annoyance so I don't push too hard to discuss it with them.