It seems to be quite a big thing right now and experience with converting web sites to be more accessible seems to be a common criteria for jobs.
My question is, why is it important?
Is it a legal issue? Can I get sued if my web site does not comply with some accessibility standard? If so, what law would I be breaking?
Is it a moral / ethical issue? Should all people whether they're semi blind or they're using pentium 2's to browse the internet should be entitled to access the right information?
Is it a user ability issue? Are there enough users in these minority categories that it's worth investing the time to cater for these users.
Is it a maintainability issue? Are applications that are more accessible generally easier to maintain?
Or is it something altogether different?