Different operating modalities are useful for providing a personalised experience and a one-size fits all approach is not the way forward. Indeed, I wonder if universal design, or participatory design just encourage a product which is acceptable to all but desired by none.
This maybe just what we need to start moving deep cognitive understandings of the Web Ergonomics of users into a form that can help us simulate and apply this knowledge to instances of Web Interactivity, sort of a CogTool on steroids.
Ask any well informed Web developer to rate how important Web accessibility is, and I’d expect most to rank it high. Ask them why, and I’d expect most to talk about disabled users, altruism, and the law, but there are more benefits from accessibility than that.