Having worn hi vis gear at work for thirty years and seen the difference, especially at night or poor light I can't see a reasoned argument for not wearing it.
Not to wear - 1 - I don't see why I should take responsibility for my own safety - it's always someone else’s fault and of course 2 - I want to prove a point [even if it kills me].
Reasons to wear 1- you have to wear something anyway [if not it can get a bit chilly]. If you ride to work cycling gear and most work gear are not the same so you can't usually use the same stuff. 2 - it just isn't expensive. 3 - it might save your life - especially at night reflective strips etc really do work. Finally there are no statistics for accidents that don't happen. To say "oh x number of motorists passed just as close" is irrelevant - the point is they saw you anyway however close they came. Only by being involved in an accident and then duplicating the exact circumstances again [impossible] with different riding gear can the theory be in anyway proved.