In my experience it's not that aircraft are unsafe, but what people try to do with them can be.
I watched the Youtube link above of the man falling to his death whilst trying to climb from a biplane wing to a formating helicopter.
One sarcastic but to the point comment from "pilotmanfisher" took my eye and it illustrates my point exactly:
"hmmm so how can we make walking on the outside of planes safer????"