I think the major problem here is that parents are blithely unaware that this is going on. If the majority of parents knew that these images and sites existed, and that their kids could access them even by accident, then the companies would face a backlash which would force them into action. A boycott of the shows and associated merchandise would upset the kids, no doubt, but it would upset shareholders even more!
There is one thing I am still bothered about, however. What kind of parent lets a 6-year-old get their sticky little fingers on a £300 piece of kit?