I think the most general statement that you can make is that if you have a person in a chair or a person with a disability that you should try to find actors with those disabilities to play the part. Much the same way the producers of E.R. make very specific attempts to hire female or black directors because the industry is so heavily weighted on white male directors. I think this translates into the storyline as well. More is done on E.R. powerfully without ever making a point. Simply by showing and not commenting we have been much more powerful.
People turn off to being lectured.
The ability to fulfill both aspects of educating and entertaining depends on the greatness of writing. Great writing will work for so many people on so many levels as opposed to great agendas. Look at great classical fictional writing. I think that kind of writing is just being lazy. No, because every great success I can attribute to is always that.