Aside from cost saving with not everyone having a HDTV, it does also make you wonder whether there is actually some secret pact that people using HDMI technology have agreed.
When I bought my PS3 from a large high street retailer, I said I needed a cable as one didn't come in the box. The sales assistant then led me to the HDMI cables which pretty much had a large dedicated wall. They basically ranged from normal, to gold plate, to crafted by god himself. I then asked which was the cheapest and he pointed it out, but it was still very expensive, I forget how much. He then, rather unexpectedly mentioned that they had a bunch of end of the line ones, somewhere else in the store. So he leads me right to the back of the store where there are a bunch of random cables and some HDMI ones for really cheap. I then say "Well I might as well go with this, as there is no difference over HDMI right...." He happily agrees with me, and that was that.
But clearly there is a big market here for cables, with HD on everything now, and a lot of people will probably be easily suckered into it.