I think the reason this story is running longer is because of the multiple serious injuries involved.
The HSE have a concept of societal - or group - risk. Society in general is more tolerant of individual people being killed or injured than groups of people. Just witness how many people are killed on roads every day, but they tend to be single fatalities, so nobody really thinks about them too much. But as soon as multiple people get hurt, 'society' views this as something bigger. That is why the HSE classifies cases of multiple serious injuries in the same accident as a major incident - they realise that this will attract the attention of 'society' - and the press in particular. Tolerable risk criteria for groups of people is lower than for individual risk - the HSE publication Reducing Risks Protecting People (R2P2) talks a lot about this, if you are really interested in the concept.
Add in the fact that the people are still in hospital, and details of the injuries are still leaking out - and you have a nice easy story for reporters to write about. Minimal work required to string out a story to fill column inches that people are interested in. You just need to look on the BBC website to see how often stories about this incident figures in the most read stories of the day. You could make an argument that there may have been less stories if there had been fatalities, and no other injuries - the story may have disappeared by now, because there wouldn't have been any more information to come out until the investigation concludes.
I must admit, I was hoping to keep the severity of this incident away from my son (who was a wimp about going on rides anyway), but it has been shown so much on TV he found out about it anyway. Hasn't seemed to put him off too much thankfully, especially as we are off in less than 4 weeks now. He did say he definitely wouldn't be riding Smiler though (not that he would ever have dared to anyway - this is a guy who, at the age of 6, screamed getting on It's A Small World because he thought it might be scary!). Just hoping he still wants to go on Rita and 13 though (suspect Nemesis is going to be a step too far for him this year).