Can you post an example of what you mean?
Japanese media is inherently formulaic. Japan never had an industrial revolution of their own, so they've had very little innovation between their classical art and contemporary art, the latter of which is largely appropriate from the West by necessity (because they have nothing else to draw on). Where Japanese (and Asia in general) exceeds is in refining Western innovations with a level of nuance only a consumer could recognize. It's like brown rice its refined, palatable counterpart, white rice. Or a home meal to fast food. So, if you want to understand Japanese art better, just explore the Western canon, since that's what it's ultimately founded on, just less refined.
Also, you're judging the entire Japanese art scene in terms of the lowest common denominator of career artist. 90% aren't even that capable: they just find that niche where they can conceal the fact they're outsiders parodying outsiders parodying the afterimage of career artists long since dead. If you wanted sincerely expressive visual art, firstly, you wouldn't limit yourself to one medium, and, secondly, you'd be exploring Japanese avant-garde (it's in the name). The issue is that most laypeople want conservative art, they want established techniques, methodology, archetypes and themes, and they don't respond well to art that emphasizes expression over established technique; thus, why everyone bitches about dadaism in museums, e.g. "my child could draw better than that" without even attempting to consider artistic intention.