I'm used to it and all my bikes are like that. Since rear shifting and front braking are done by my dominant right hand, and they are much more important or used more often than rear braking and front shifting, I think it makes more sense for right handed people.
I think it is what you are used to, but having borrowed a bike in the US once while on a business trip with the opposite set up, it sure feels a bit strange. I think it is driven by which side of the road we use and the ability to do hand signals, rather than dominant hands. Of course most cyclists I have seen in Tokyo wouldn't know a hand signal from their a**e......
It is just what you are used to.
You can argue it either way and people actually believe what they spew to actually be believed like science.
I ride motorcycles - right hand front brake.
I ride bicycles obviously - right hand rear brake.
I have NEVER swung my leg over a bicycle and confused it for a motorcycle, so I don't need them set up the same.
Regarding dominant hand - I have no desire to have my dominant hand on the front brake of my mountain bike (Note I am an MTB Rider first). In a panic situation - I am OK not flipping my bike. On or Off Road. I actually am ok using my dominant hand to drag the rear brake and my left to bump the front to make the safe stop/speed change. I would also argue the rear brake on a MTB is used more than the front, so again - the dominant hand is on the most frequently used brake.
That said, I have ridden bikes with the brakes set up the opposite way. After a little time riding - I am mentally adjusted.
It is very rare you ever grab a handful of brake, so if you squeeze the "wrong" lever in regular riding, you quickly get a reminder with no drastic problem.
The bike shop here does them all like that. I remember being told by Enosan at the bike shop why. But in reality I think it is so he recognises a bike that he's built when he puts it on the stand. Don't want to be criticising the workmanship if you did it yourself!