I will answer this. I take mine because I think the risk is extremely minimal so long as the overt peanuts are not being served on the plane. I wipe down the tray table and armrests and I book the first flight in the morning because that's probably the most clean a plane is all day. My son has been around people all his life that eat peanut butter sandwiches or other candy and he lived. He made it through daycare, school, and halfway through college eating in groups and the smell or proximity did not set off a reaction despite being one of the most highly allergic out there.
If, after all my studying of this, I felt that his life was in danger I would not fly and I would not put that on anyone.
With the RyanAir incident I am not 100% convinced yet that the man 4 rows in front of the girl was the culprit. It seems more likely that she may have picked up some residue on the tray table or armrest and ingested. This doctor's commentary at this link is pretty good:
http://allergicliving.com/2014/08/21/anaphylaxis-in-the-air-two-recent-airline-incidents/
So while I do take all the precautions I can, I try to not to unduly make demands that aren't founded in evidence and cause others with competing issues hardship. I hate how the airlines handle this by not telling anyone till they are on the plane. That is totally unfair to others with health issues that are relying on the snacks they brought. It's a shame because it just causes grief for everyone. But then again, I don't have a problem with a diabetic eating peanut butter on my son's flight. When he was a baby and wiggly, I may have asked to be moved to another row but we've always traveled in groups so my son has only had family members around him on flights.
I will probably get flamed by the PA folks, but I am very doubtful that having random/few people on the plane "breaking the peanut free" rule or needing that peanut butter sandwich is going to cause death or difficulties in the overall peanut allergic population. I just don't. Of course getting to this place has been an evolution for me. When I first found out my son had this allergy, I fell into the panic for quite some time.