In all of my modeling I've noticed a real sense of sameness and uniformity. People aren't all the same. I, for example, am Autistic and have Klinefelter's 47-XXY (physically I look like most other people, so it wouldn't have been very interesting to focus on people like me). So it just seems like there should be more representation of other types of people in SD.
There isn't any particular reason I started with Downs Syndrome, but it is as good of a place as any. Hopefully people use it for good, as was intended.