Living in Japan is really expensive already.
Perhaps my experience in Japan is a bit different.
For day-to-day expenses, housing, transport, I would say Japan is on-par if not cheaper than other developed countries.
When it comes to imported goods (or even electronics made in Japan), the prices are usually set in USD and adjusted back to JPY which means to the average Japanese, yes some luxury goods seems more expensive due to the relatively lower overall salary in Japan.
To the regular Japanese, daily living expenses are not that high. You can get quality goods even on the low end of the spectrum. Even in the US, once you go too cheap for food you have to wonder.
For a foreigner or higher earning people, Japan is actually relatively cheap compare. Housing is pretty inexpensive compared even major cities in China.
Apple products certainly are not expensive in Japan. It's due to their currency fluctuations Apple has adjusted the prices to compensate, but again like all imported goods it only seems expensive relative to the Japanese salary, but definitely not more expensive to the US...
What Japanese people are more sensitive to is quality. They've got a nose for it, so to speak. The XR is basically low quality goods compared to the X/XS is why they are not buying them. I'm not saying Japanese people don't care about price; everyone does. For $750 USD what other choices are there?