Actually this and that giant iPod Speaker was probably two of the most subtle yet genius decisions Apple ever made.
They demonstrated to accessory manufacturers that there was a lucrative market for them to get participate in. Not to mention putting "facts on the ground" about expected sales, profit margins etc for them to build their product strategy around.
I'm pretty sure there were already accessories on the market at that point. I don't think the iPod Hi-Fi was the first high-end iPod-oriented speaker system.
They demonstrated to accessory manufacturers that there was a lucrative market for them to get participate in. Not to mention putting "facts on the ground" about expected sales, profit margins etc for them to build their product strategy around.