I beleive we started seeing more reflexed risers when the bows started getting shorter and shorter. Then there came the parallel limb design and still more reflex was designed in to keep brace heights to acceptable levels and still provide great speeds. It's what is selling to the masses today for generally one purpose,, hunting. In bowhunting, where most shots are taken from a tree stand or ground blind, the ranges are short and "personal". My longest shot ever at a deer was 28 yards and my closest has been 3 feet from the base of my tree. Do I need a long ATA bow with a deflex riser for these shots?? NO WAY My newest hunting bow, the Allegiance has close to 3 inches of reflex in the riser but I can still shoot 4 inch groups at 50 yards with it. Do I need better than that for hunting? NO,, as a matter of fact, I can shoot the Allegiance just about as good as ANY bow I've ever owned in the last 33 years.
I'm no paid pro shooter, but if I was and not hunting for food,, I'd probably be shooting THE most forgiving set up I could find. This probably WOULD be a deflexed riser bow with a long ATA and 8 something brace height.
For my hunting bows,, they will continue to be short, light and fast with heavy arrows but must be quiet shooting