"Most"? Where did you get that idea? "Most gaming mice" or what? Most of the users aren't gamers.
> that means a PgDown button (I guess it is mostly that direction) on the mouse is missing.
Of course is missing: "normal" (as in the most common) mice have only 2 buttons and the scroll wheel.
The scroll wheel never moves one page up (or down), but just some small number of lines, so the most common operation is then impossible for the most of the users just because a developer (who probably even "lives" in his terminal for most of the time, never lifting the both hands from the middle of the keyboard) thinks that everybody has exactly the gear that he has.
- left click - page up/down
- middle click - go directly to this point.
Moving one of these to the other is confusing and a loss of useful functionality. Reminds me of "chesterton's fence."