I stopped off at the Winchester booth during SHOT Show and spoke with one of their engineers about the company's new "Rooster" pheasant load. I had shot some at Range Day and the engineer asked me what I thought of it. While it did what it is advertised to do, it gave me a good whack on the shoulder, too.
"I like it," I said. "If it had an eighth or a quarter of an ounce less shot and was 100 fps slower so it kicked less I'd like it even more."
"I agree with you," said the engineer. "But no one would buy it."
Whether consumers demand heavy, high velocity loads and ammo makers oblige them or whether ammo makers advertise those loads and create the demand is a chicken-or-the-egg type question. Whatever the case, hunters have voted with their wallets for heavier, faster loads and that's what the ammo makers give us.
At the same time, guns keep getting lighter.* The inevitable result is more recoil. It's simple physics, easily quantifiable on any one of a number of online recoil calculators. When payload and/or velocity increases, recoil increases exponentially. Subtracting gun weight increases recoil, adding weight reduces it.
The problem with more recoil isn't that it hurts. It's that more recoil makes people shoot worse -- even people who think recoil doesn't bother them. A gun that kicks hard is very difficult to control for a good followup shots. In the long term, recoil beats into you bad habits like lifting your head or dropping the gun away from your face as you pull the trigger. Both are your body's way of trying to get away from the gun that is hurting it. Both are also excellent ways to miss something with a shotgun. Most people aren't even aware they commit these errors. They can't understand what happened when they empty a gun at a bird that flies away unscathed.
Sometimes I hear people who have been on a missing streak say, "I'll get some 3 ½-inch shells and put more shot in the air."