I have friends who blind. Blindness isnt fine. If there would be a way to heal the blindness, they would do so immediately.It deeply saddens me to hear that.
I am nearsighted. Being nearsighted is fine.
This is the problem in the first place: "measure up".A lot of people do hate themselves if they don't measure up to what society tells them they should look like.
At the same time, is poverty good? No. It needs to heal or mitigate. Is blindness good? No. It needs to heal or mitigate.
Stop calling harm good.
The narrative explanation, like the narrative explanations for most "unique" PCs (see also: good drow), is up to the player.@Umbran
A difficulty is, D&D includes fantasy cultures. Even ones where magic or other technology can remedy blindness or have utopian economies, or so on.
In such a culture, blindness implies a choice to be blind, which requires narrative explanation. Or perhaps it is a powerful magic, and community lacking high enough levels to counter it. Or it is a recent injury, or so on.
I value inclusivity. There needs to be ways that make narrative sense.