Accessibility: You must be aware of your own stereotypes
Many (many many) people in tech I talk to who are unfamiliar with Accessibility invoke internal stereotypes about disabled people. This is called ableism, and like sexism or racism, it means that -- consciously or unconsciously -- a person thinks of another person as "lesser" or "other".
In my article, "Reframing Accessibility for the Web" I try to make the reader aware that ableism exists, and that it interferes with our support of accessible design by denigrating the value of the people accessible design serves. In that article I suggest that if you can't justify writing accessible software as an audience need, then you should reframe it as a technology need -- you need your software to run on these pieces of hardware (keyboard, mouse, sip-and-puff, screen reader, etc.) regardless of what you think of your users.
Would I prefer that everyone tear up their internal stereotypes and build accessible software because everyone needs it? Hells to the yes I would. But I've walked into too many executive meetings where the first thing I was told about Accessibility is "it has to have a business value, it can't just be the right thing to do", so - yay capitalism? Besides, half the time we don't even know what our internal stereotypes are until someone points them out to us. The best way to uncover them is to expose ourselves to different ways of thinking, which happens really fast when we try to use input devices we've never used before. We'll never be substitutes for our disabled users, but we might at least see some of the stupider design mistakes we've made if we at least try to test our software on multiple devices before shipping.