I think that lack of failsafe is exactly what is wrong with the ride itself. There are ways to design the apparatus so that this failsafe is there. Freaking out is part of using amusement attractions. There is stress involved, especially among people not used to traveling all over for different rides and thrills. You can't expect everyone to behave in perfectly rational ways when under such stress. People bite off more than they can chew on rides all the time, or get egged on to ride by friend/family. It's the job the ride design to take this into account and make the experience safe. The device should not allow a person who suddenly becomes freaked out to accidently kill themselves.
I completely agree with everything you stated in your post. With a ride like this, you HAVE to anticipate that someone might get scared/panicked at the last minute and resist the jump. This is a natural human fear response. This woman did not have to die if this ride was built properly to account for this. Total fail on the ride manufactures part - no question about that in my mind.