Pete,
I'm usually on the same page as you but in this case, I think you're being a bit extreme. Yes, there are definitely people for whom the attraction is not suited so they should no ride. If they do, yes, they might have ill effects. HOWEVER, the same can be said for Rock & Roller Coaster, Tower of Terror, Star Tours, Body Wars, etc. etc. Many people can experience this attraction with no ill effects at all.
And having been on this attraction numerous times, I can say with assurance that there are several warnings before the ride iteself, beginning with signs at the start of the queue and statements with pictures during the preshow that allow people to decide if this is something that they should avoid. Furthermore, I've spoken with cast members who have stated that in exit surveys most respondants who reported feeling or getting sick admitted that they were either already prone to motion sickness or had disregarded the clear warnings not to look around or lean forward during the experience.
AnnaS - did you get sick before or after closing your eyes? Because if you keep your head straight and focused on your monitor, it should "trick" your brain regarding the spinning and not feel it. Obviously this doesn't work for everyone but that is the theory. If you close your eyes while riding, however, your eyes are no longer tricking your brain and will make you sick or exacerbate any feelings of queasiness that may have already begun.
For the person who asked about the G-forces, they occur in spots during the ride and are of a longer duration than the start of RnRC.. I daresay they are more intense as well but it may just feel that way because of the duration. I can't tell you whether you should ride it - I will say, however, that it is only 4 minutes.
I guess what I'm saying is that yes, this ride can make some people feel ill. However, I really don't believe this is any worse of a problem than for other thrill rides.