You've brought up a good point. I think the warning posted on the ride has become more of a generic warning found on ANY ride today. The precautionary warnings found on a wooden roller coaster would probably be also found on a carousel. Also those warning signs are treated at the same level as a software licensing agreement that you have to click on the "Agree" button before installing it. Do you take the time to read the entire SLA before installing it? I usually don't, as it has become very generic.
Also, at Epcot, Test Track and Mission Space are the only 2 thrill rides at the park, while the rest of the park are just people movers past scenery and theaters. Since the majority of the park are gentle rides, people are led to believe that Mission: Space is just another gentle ride. Maybe they should put a sign up on every door that leads to the capsules that says in big bold letters: "Did you read the warnings about this ride?"