Your average adult isn't going to feel any fear or trepidation about going on a family coaster and I don't know any adults who fear those Disney attractions. I say this a wimp who does get a touch nervous on Incredicoaster and Ghost Rider and other standard coasters. Hang Time at Knott's is about my limit, and that's pretty middle of the road when it comes to standard coasters.
I started out very fearful of fast rides and rides with drops. The "drop" is the same sensation as "falling" which triggered a response from my body which said, "OHMYGODWE'REGONNADIE!!!!"
What helped me to start getting over that was:
1. watching POV of the rides, especially the lights-on versions for the ones in the dark.
2. riding Flight of Passage over and over again.
When I saw that the 'fall' in PotC and FEA was just like a playground slide, I had to tell myself it's not that bad... its just a big slide. And no longer dreaded the drop.
When I read that Test Track was just 60 MPH, I was able to say to myself, "I can ride in a car at 60 MPH with the top down... no big deal."
When I saw a lights-on POV of Space Mountain, I realized it's almost a kiddie ride with no big drops. Just really annoying high speed turns that you can't brace yourself for because it's in the dark.
I knew going into Flight of Passage that there were no big drops. But the big drops in the ride were illusions from the 3D screen and being tossed up in the air no more than 3 feet. I rode that over and over again until I welcomed and enjoyed every 'drop.'
After that, I was able to do 7DMT. No big drops. The swaying car actually made the ride easier since it turned the lateral pull into just a slight positive G force.
After seeing online that BTMR and Space Mountain had no big drop, I was able to ride them. I like BTMR because I can see and brace myself for the sharp turns. And I hate Space Mountain because I can't.
Now, SDD is nothing to me. Cosmic Rewind is a blast.
Everest has the problem of lateral punches in the dark. Not doing that again. TRON is great because it's just mainly height and speed and no drops.
Still haven't braved RnRC yet. I'm dreading the inversion. And I'm guessing there's a lot of lateral punches in the dark.
Anyhoo... I welcome the newer coasters because they are all laterally smooth. No more whiplash. Which is a problem for a non-coaster ride... DINOSAUR. Good riddance.
I assume Monster Inc Door Coaster will be another nice smooth family coaster.