Regarding the nausea issue...
I think the main point I and some others have is how some on this thread are (I believe) blowing the issue out of proportion. I'm not saying it's not "a thing". And it certainly seems to be something more common than Disney expected. However, on the flip side some posters seem to be describing it as something that invalidates the entire ride or suggests it is so egregious that the how setup needs to be scrapped and start over. I do think it is telling that the same posters seeming to focus on this have a significant overlap with those who have complained about the ride all along (and to be fair vice versa those who defend or minimize it seem to have been consistent defenders). IOW I think there's a lot of confirmation bias going on.
The big question is "how common of a problem is it?" - I don't think we can really answer it at this point. Heck Disney themselves might not really be able to tell though they obviously have better info than us silly message board posters. Eventually information will leak out among the usual sources and we will see how frequent protein spills occur or how much complaints they get. I agree that the barf bags are concerning, but the fact that they appeared opening day makes me feel like they are more of a precaution than an necessity - like this is Disney's way of "covering their butts" to soften any complaints. They know its new ride and they want all the coverage to be positive, so they at least want to try to "nip in the bud" any negative press of Disney isn't doing anything regarding riders getting nauseous.
My gut feeling (ha!) is that as the more people experience the ride, you'll get self selection and a better word of mouth about who can ride and not. And I personally believe that the number of people who can ride roller coasters (Everest/Space/RNR level) but will avoid this will be relatively small. I am skeptical that this is a M:S situation and more akin to Simpsons. But I can stand corrected once more info and experience comes out. I expect Disney's reaction to this to be most likely having some extra warnings at the entrance to the ride as opposed to actually changing anything with how the ride operates.
Finally, the idea that Disney should have anticipated this more seems extremely odd. I'm not sure how they can really tell what will happen with large numbers of different people until they at least have soft openings. Riding an out in the air prototype doesn't tell much about the specifics of this situation. And I would expect that it is uncommon enough that the relatively small number of testers that would have ridden pre softs wouldn't be able to be a significant enough sample size.
In an idea world to me, perhaps Disney will be fine with GotG but feel that Epcot needs a lower intensity more welcoming thrill ride as well to compliment CR and will finally build a Matterhorn-esque Mt. Fuji coater in Japan. Just dreaming....
Your're probably right that Disney did not have any intention of making guests sick. I guess that being the result doesn't bother me as much and I relegate the need for nausea bags to such a minor outcome as not to be worthy of discussion IMO. I think there are more reasons to critique e.g. the ride costs, development time, IP in EPCOT, shoehorning a ride as an out-of-this-world pavilion, etc.
