Without qualifying what precise conditions that 85% are in, we cannot draw any conclusions about what this number says about us as a society. It's in my view highly emotive to just put that number out there without providing this context.
But you've gone ahead here, like many others, and talked about individual choices, rather than the meaning as a society. It's like any kind of action that takes place on a wide scale, you can't simply put it down to individual choices without looking at what the wider pressures and underlying beliefs are.
It's not dissimilar in some ways to widespread abortion of girls. There are very understandable reasons why, in some cultures, individual women and families make that choice, it makes a lot of sense from an economic perspective. Sometimes they feel they have no choice because they simply cannot afford to do what is expected for more girl children, or their futures will be insecure without boy children. Those are serious considerations for a family, but they reflect bigger problems - strongly embedded traditions and culture that mean families have economic burdens they can't cope with, and that care of elderly parents depends on sons, along with a cultural preference for boys. Together, at the level of population, these kinds of things mean talking about these as individual choices is a shallow analysis.
Our culture inadequately supports families with disabled children, and inadequately supports disabled adults. We struggle with putting money into health care generally, but not, really, because we are a poor society. We tend not to value those who don't seem to measure up intellectually or who can't fulfil our idea of success - we say we do, maybe even think we do, but that's not what we see reflected in our culture, people are very aspirational about children. We are very uncomfortable with death and tend to want to avoid it in a way that is not always healthy, we have a very definite set of ideas about what counts as a fulfilling life and "short" doesn't really count. Even things like smaller families may be relevant, as it is now in cases of sex selective abortions. We are afraid of suffering.
These things not only push people in a particular direction when they make choices, in some cases unwillingly, they shape us and what we value as surely as those in a society that chooses boys over girls are shaped. It's not just individuals making independent decisions, there are a lot of cultural assumptions about what kind of life is a good life or one to be valued, and that tends to get lost when we just look at it in terms of individuals.