I think this is partly caused by living in a very human-shaped environment, and we are unaware of how dangerous nature was before we tamed animals and cultivated plants.
A great example of this is almonds.
Personally, I enjoy how the most powerful toxin known to man is entirely natural and produced by bacteria.
Of course there are exceptions, as I said. But still, if I blindfolded you and forced you to pick something at random and eat it, would you rather do so in a natural wilderness or a DuPont lab?