Switch is doing crazy well in Japan. I think the Japanese understand the console better than the American audience does.
To me it looks like the opposite.
Given the size of the markets, Americas and Others should always have more sales than Japan, about twice as many. Proportionally, Japan is the best territory, but the ratio to other regions isn't as worrying as for the 3DS. The 3DS's lifetime sales will have essentially one third in every region, but something in the ballpark of a 20/40/40 split for Japan/Americas/Others would be more appropriate. So far Switch is at approximately 25/40/35, so Japan is punching above its weight (but not crazy strong like asserted), America is where it should be (so Americans aren't understanding the system better than Japanese) and Others is on the weak side. The noteworthy difference is between Japan and Others, but there's no complicated explanation.
It's clear since a good decade that portable consoles are perceived as better value in Japan, so the Switch's price isn't much of a hindrance. That's not the case in Europe (the majority of Others) and the price of the hardware with its unusual €329 hasn't been as good as the $299 price tag in the USA (the majority of Americas). Additionally, Nintendo still has a lot of work to do in Eastern Europe as far as distribution and marketing presence are concerned, so Others proportionally lagging behind a little isn't surprising.
Having said the above, another important factor in perception are the sales relative to competition. Since the PS4 is performing in a mediocre manner in Japan, it makes the merely good sales of Switch look amazing.