Bingo, you are WRONG again.
The reason the 2hbh is used more often in pro tennis is because all the little kids who were learning tennis as little kids could not swing a 1hbh with control and power.
As the little kids grew up, they stuck with their 2hbh's, not changing to 1hbh like Sampras.
Just like they stuck with their baseline game, choosing not to come to net unless forced to move forwards.
Why adopt anything new, have to relearn new things, when what you're already doing sorta works. Works for #1 anyways.