I know that Ikea's instruction style has been intensely influential in the home furniture business when I go buy a set of curtain rods at a different store, or an "assembly required" vacuum cleaner at a garage supply store and they all feature copies of what look like Ikea instructions. Simple line-art, no words (saving having to print assembly instructions in 11 languages) etc.
And then when I set out to actually follow the instructions is the brilliance of Ikea's instruction design made clear. Curtain rod instructions? I have almost no idea what they are trying to convey to me, random screws and indecipherable brackets make putting them up a chore. Vacuum wasn't much better, I'm still not sure I have the right hose in the right place.
But put together an 1100 piece Ikea drawer unit? It's as much fun, and as simple, as building a Lego Millennium Falcon -- and they've managed to describe the process unambiguously, and in only as many steps as necessary (around 30). Each little connector is absolutely clear, the shape and sides of similar looking pieces are obvious, multiple steps (when absolutely clear), are combined into one.
The instruction manuals are virtually parts of a piece of audience participation performance art.