I believe that the motivation behind avoiding the negated boolean is simply readablity.
It is simpler and more understandable to reverse the if / else statement. A future reader will have an easier time with an
"if TRUE" than with an "if not TRUE" construction.
Of course, the functionality is the same both ways, but you always want to assume that sometime in the future some drooling moron will need to understand and modify your code. And
you should try and help the poor benighted sod.