That is not a good answer in my eyes when mangas / animes like Fist of the North Star and Berserk are very gory - especially in Berserk's case. Berserk's protagonist Guts would fit extremely well in a MK game, lets just say that.
I'm willing to say instead:
A) Lack of advertising and having more competitors during the initial period in the early 90s. Contrast Street Fighter and KOF, for instance.
B) (IIRC) A prevailing view within Japan - especially with more conservative people - that video games should be family-oriented and anything more mature than say 17 is shunted hard into the adult corner. Which does limit how much they can advertise etc. I'm not entirely confident that this is indeed the case, so I'm asking
Ayumi Tachibana for verification.
C) A rating board that is much more proactive than the ESRB when it comes to ratings -
CERO's standards is something that Resident Evil and the Last of Us has followed, after all, with both removing some gore in their Japanese versions. And conversely, MK's developers probably don't want to release a gore-less MK. So it's an standstill on that front.
As such, there's been a lack of Japanese MK localizations and no releases from
9 Trilogy, (thanks
G
Guynamednelson
) onwards - from a Japanese POV they're still available on Steam, but with no Japanese localization.