Why are video game and computer joysticks of the seventies and early eighties right-handed (eg. Atari 2600, Odyssey 2, Apple II), and game pads, since Nintendo Entertainment System to today, all left-handed?
I asked the same question over at UX: https://ux.stackexchange.com/questions/57630/why-are-most-game-controllers-left-handed
Lots of speculation but no real answers.
Larry Bundy claims the change was made to make arcade games more difficult, and thus increase revenue by making it harder for players to master each game. He doesn't offer any evidence or citations though.
It seems that there is no good answer for this. The earliest examples of left handed controls I can find are arcade machines and the Nintendo Game & Watch, but it's hard to know if they were the first.
Arguments claiming that more dexterity is required for operating buttons don't hold up - the original Famicom had only two buttons, not exactly a challenge to use.
I've started building my own right handed controllers and can confirm that they are much, much easier to use and give me a significant edge. I am right handed.
A gamepad is not ergonomically the same as a joystick.
A joystick's stick is normally operated with the dominant hand, while the other hand holds the body (where it can operate the fire button). Since most people are right-handed they prefer the stick on the right.
A gamepad is held by both hands, so it doesn't matter which side has what buttons. However since the direction controls are usually held down more than the fire button, having them on the left means that it is held more in the left hand - just like a joystick.
And of course there were exceptions. Some joysticks had buttons on both sides or in the middle, others on the top of the stick. I have a Mindscape Powerplay which is held from below by a handle. Even though I am right-handed, I prefer to hold it in my right hand and operate the stick with my left hand.