"Because we've always done it that way" is not a rational explanation of why something shouldn't be changed for a good reason.  Exposing yourself and your family and friends to a paralytic poisoning that has a 70% death rate if untreated (think: during a disaster) doesn't make sense when you know better.
 
The fact that generations of people I know have done this as a way of life for hundreds of years without any incidents is exactly why I will do it.  I have gotten food poisoning from an IMP before.  Those are supposed to be perfectly safe.   Silly me but I trust food I prepare far more that stuff squeezed into a can from some factory most times.  Hell, My neibors cat died a few years back from tainted cat food.  Guess I am putting my life at risk every time I eat something out of a can as well.
I can look up stuff on wiki all day long and provide you with a bunch of percentages about this and that but it means nothing.  Some people learn from books and some people learn thru generations of experience.