A couple of thoughts that haven't really been brought out. A World War enamored a lot of folks with "Fire-Power". When the pumps & Semis were first introduced they cost as much as a good double. The switch did not come because of economics at that point, it was the ability to throw lead Faster.
With the 3-shot limit for migratory birds & even some states instituted it for all hunting, I know TN did for a long number of years, many decided to go back to a Two-Shooter. Many were younger shooters who had never used SxS guns & they "Thought" they could not shoot as accurate with the SxS, so went with the O/U.

Personally, I hunt for the fun, I'm not at war with the game. Nor am I in competition with any co-hunters I may be with. There simply is no shotgun that touches my Soul like a good SxS, so I'll shoot one till the day I can no longer shoot anything at all, Period.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra