What I dont like about these scenes is the splatter exaggeration. I would have lived with it had they been gushing from the neck or other major arteries but a belly slice doesn't seem like the gushers expressed in this scene.
You're not alone. When this came out the thing people complained about almost as much as Beat Takeshi's blond hair was the CG blood. I really liked the movie, but it was a shock for some fans to see the normally schlocky character portrayed in an actiony blood fest.
My favorite guy in all Zatoichi movies is the one who despite watching dozen of his yakuza brothers get ripped apart still makes a halfhearted charge into battle. Everyone knows he's just going to provide Zatoichi or the pissed off ronin a nice opportunity to show off his ability to creatively hand a dude his ass.