The only thing I can think of on that one is that astronauts are generally put through simulations where things go wrong, so they can practice how to correct and prevent it. Nevertheless, it makes for a kind of unexciting storyline. In most (if not all) Disney attractions (and Universal ones too, for that matter) we're pretending to be doing something. Whether it's encountering pirates, flying through space, etc. But on M:S, we're pretending....to be pretending. It's kind of lame. The only explanation I can think of is that they didn't want to go to the trouble of disguising the fact that it's a simulator. So they just built it into the storyline. It's kind of like how on EE, they didn't want to spend more money on an additional Yeti, so they built it into the storyline that you only see him once.