It's the same with brakes. Right hand rear, means you're queer.
Or continental/american (but I concur it makes more sense if you are right handed to have it british way) 😉
The French however, because they weren't into duelling and time-keeping, obviously drive on the right instead.
Stoner in fail again. French use to horse ride on the ride. Until Napoléon decided that people on his empire would drive/ride on the opposite of the British. And so did everyone else who wanted to upset the British Empire.
As said above, it's easier to put on/set up and you are less likely to damage it. As for wearing it the other way round (facing down), I found it less painful on the bike and I tend not to scratch it/damage it too.
Mind you, since my watch died I have solved the problem.