Japanese vs Western culture is a factor for sure, but Nintendo of America also had a 95% retention rate and a 10 years average tenure so it's not like the Western side of the company is having problems either.

Indeed. There must be some good employee culture and perks to keep that level of retention.. Which says something, which is in stark contrast to how Nintendo routinely attacks and behaves negatively towards content creators and artists.

To put that into perspective, that's a better retention ratio than even Valve which has historically been a very positive workplace.

For context, the average annual retention rate for Japanese companies is 70%, so even in their own country, they're way above the average.

Apparently key factors are high pay, excellent benefits and work conditions, and just the fact that a lot of people really want to work for them:

https://biz-journal.jp/company/post_358805.html

Is that so?

https://www.statista.com/statistics/349038/employees-at-nintendo/

https://www.gonintendo.com/contents/43274-nintendo-ranks-3rd-amongst-job-seeking-graduates-in-japan

https://nintendoeverything.com/nintendos-new-development-building-now-open-for-business/

https://www.videogameschronicle.com/news/nintendo-confirms-that-its-new-development-centre-has-been-delayed-to-make-it-bigger/

It is just a mater of time that they succumb to the AI pressure and lay off staffs. Shareholder would like more dividends if they realize that layoff can make it happen.

Nintendo is still in a fortunate position where their biggest shareholders are within Nintendo itself.
There’s disliked investment firms like BlackRock involved, and the Tokyo Bank are involved, but it’s still spread pretty wide and Nintendo can do what pleases themselves.

It is. They save far more money than they invest

I'm not implying they should change how they manage their bussines because it's working. If the main shareholders were American they would have already take all the profits to invest in other ventures 

Non-unionized corporate labour forces combined with reduction in competition of industries in Western culture has allowed for significant abuse by said non-unionized corporations. Japanese culture is different, there is an honour and loyalty code there. Loyalty doesn’t mean shit in Western culture, less than shit on North American side of Western culture.

That would be my educated guess.
The egregious CBS and Paramount merger that allowed the Trump administration to coerce them into getting Colbert fired is just another example of this decay in western corporate culture. But, I can’t be the only one who has witnessed employee firings being used by executive management as a means to show that “they can make the hard decisions” to shareholders, with a manufactured context to make it look like this is a positive and necessary thing rather than just game move so they can get that bonus, raise, and/or promotion. Much of the time, these people didn’t do anything wrong, nor did they cease to become useful: it’s just that I’m the manufactured story, this became the case, and they pretend like letting these people go is painful for the executive.

In short, we suffer corporate systemic psychopathy.
And if I may get political for a moment: break up the corporations (Teddy) and/or legitimize unions (Franky). Elizabeth Warren championed both directions, and she would have won if the Bernie Busters hadn’t teamed up with the Conservative Democrats to shut her down when she got too popular. It was perhaps the largest propaganda campaign by far from the faux-leftists who, at the time, comprised the Bernie or Bust cult.

In other words, it’s not Nintendo or Japanese exceptionalism. It’s the profound weakening of western economics. The extreme freedoms can lead to rapid growth, but then a few bushes overthrow, and everything else rots and dies… including all the lower branches of the giant corporate bushes, even while the upper echelons are green and lush.…. We don’t need mergers, we need chainsaws.

They have invested in other ventures; over recent years they have branched out in theme parks and movies.

As for hiring more staff, they have done so constantly for years:

And they grew to about +50% what they were when they began the Switch generation. This honestly pretty insane considering what this industry is going through especially in the West.