What I would challenge you on is this...why isn't it moving more forwards, it could still be growing, innovating and looking more into the future, it's population could and should be growing or at least quite stable, but it's not.
People are overworked, not having children [1], the education system isn't really optimal (favors rote learning over everything else) and there is a lot of loneliness.
I do agree, it's a good place, even a great place, I love it, but it could be much much better at the same time. Does it need to be better? Maybe not, that's hard to say.
What is a concern is the declining population, a lot of the stability comes from the hard working, financially conservative, older, dying generation of people and it's not getting replenished anytime soon. The country is holding up well, but IMO if you look carefully, things are aging in Japan and I don't see where the demand for new things, infrastructure, ideas etc is going to be coming from.
Honestly, people make comments about Japan like, it's harmonious, culturally cohesive and well functioning are seeing it from the outside, which, like everywhere else always looks a bit prettier. A lot of the harmony does come at the cost of people's inability to express themselves. There's a lot of "personal injuries" on the Tokyo subway, I have a feeling a little bit of that comes form repression.
I'm definitely not saying it's a bad place, I'm saying it's probably not dissimilar to many other places really, there are good aspect to it and there are bad. Mostly people think it's great because they don't and can't really understand it. Japanese language isn't easy to grasp and people rarely tell you what's on their mind even if you can speak to them.
I believe the discourse in the west is harder to cope with on a personal level, but it is and important part of democracy which I do feel is lacking in many part of the world, including Japan. I love the harmony I experience when visiting, but something inside tells me change is important, at least if only occasionally.
Interesting times ahead no doubt.
[1] https://asia.nikkei.com/Spotlight/Society/Japan-leads-world-...