Of course Superfeet would like to argue that eighty-percent of the population have dysfunctional feet and need their expensive footbeds! Things go better with Coke! Daz washes whiter! Alas, it is a claim with no evidential basis, which is why they had to withdraw their adverts from TGO. Your personal endorsement is not sufficient to comply with the ASA rules. You can ask TGOs advertising department about the complaints to the ASA - here are the dates. I've probably still got the correspondence with the ASA if you are interested, though I think you should publish it so that your readers can make their own judgements.
I have not argued that over-pronation might not be a problem for some people, I dispute the claim that 80% of people suffer from it. None of the four links you give make that claim either, so I haven't got a clue why you quoted them.
Let's suppose that pronation is normal. And that there is an average amount of it. Just about half of the people will pronate more than average, and the other half less. So how can 80% of people over-pronate? What do you mean by over-pronating? If most people do it, isn't it, well, normal?
I have noticed that when climbing, my hand stretches quite a lot when I am hanging from holds. Does this mean I need Superpalms? Or is it just how my hand is supposed to work? The stretching could be a sign of flexibility, in which case I would be glad, or it could be a sign of weakness, in which case I would want to strengthen my hand. But attempt to restrict it mechanically when it isn't broken? No!