I guess it comes down to "Shoot the Highest weight you can draw comfortably"......if you CAN draw a certain weight easily then why lower your performance by shooting a lower weight just to shoot a lower weight.
I know in a perfect world you may not need the extra 10 or 20#'s of draw weight, but shoulder blades, spines, and ribs aren't really a perfect world.......
I shoot 70#'s on all my hunting bows because that's what I feel comfortable with......bonus that I'm getting some extra usable energy.
If you can draw a certain weight in odd positions, cold, under pressure and hold on target for a minute or 2 if you have to, then by all means that's the weight to be shooting.
Don't handicap yourself because you "Probably don't REALLY need it".