I am very much in favor of sort of vague rules that D&D (and, better, Tunnels & Trolls) have for combat, because it doesn't bog the game down when you get into a fight.

Tunnels & Trolls didn't use polyhedral die only d6s, women weren't expected to be breasting boobily in boob-plate, they were expected to be as strong or stronger than men, there are kindreds instead of race, and you could play it solitaire.

Then we get Tunnels & Trolls and it completely flips that onto its back. You can be an adult dragon, a living skeleton, or even a fairy from the jump if you wanted to. Neither of those is expected to be one class because you can move your score around.

It is!

Isn’t T&T also big in Japan?

In order to inherit and develop the historical masterpiece, we need not only love but also a certain philosophy. Rather than bringing in rules from the trends, you need to consider what should be kept. I hope that you will produce a work that everyone will agree is a inheritance of that classic.

Tunnels and Trolls (Ken St. Andre, 1975) broke the fourth wall and repudiated most D&D truisms. Mind blowing at the time. I see it as a predecessor for sure.