Some more examples of affordances
Web designers should do their own HTML/CSS, from the Signals vs. Noise guys, argues that different design tools -- HTML/CSS vs Photoshop -- that can all be used for the same end -- mocking up web pages -- nonetheless have different affordances (though of course they don't use that term):
The web is a world of constraints, the materials of HTML and CSS flex and give in ways that encourage particular styles. And being able to understand and bend within that scope is what makes a design feel native. Designers who work directly with the materials rather than through simulated environments like Photoshop are at a distinct advantage for making that happen. ...Some more examples. Architecture and interior decoration have affordances, that effect things like mood and attitude (Alain de Botton's The Architecture of Happiness look at this). So does music. And clothing - wearing a suit vs wearing a t-shirt and shorts.
If the concept of affordances can apply to such diverse things, doesn't this mean that it must have little utility - to be spread too thinly, so to speak?
The concept is meant to provide a way to talk about the fact that things can shape our experience. I think that we neeed to recognise that this does happen, and is a general part of our lives.
And I think it is easy to overlook this if we only see particular cases and describe them in their own terms. We can be aware that a building can make us feel a certain way, without really acknowledging that our environment can shape our experience.
That's why I think we do need a general concept. That would also help us to see instances of it in situations we hadn't thought about before.
That general concept doesn't have to be like a theory that acounts for how all of the different cases actually work.