As a French guy, I like the "grater" knife, I may even buy one, but the "right angle" one feels weird.
But I may have an alternative explanation. The article talks about order and Japanese sensibilities, but to me, a right angle cut in a butter slab doesn't look particularly pleasing.
Instead, what I think it is to make precise cuts easier when the butter is hard, for example if it came out of the fridge. In this case, it can require a significant amount of force to cut through the slab, and making a straight cut can be difficult. With the tool, you push straight down, so you can use more force. And the right angle shape stabilizes the blade during the cut.
But I may have an alternative explanation. The article talks about order and Japanese sensibilities, but to me, a right angle cut in a butter slab doesn't look particularly pleasing.
Instead, what I think it is to make precise cuts easier when the butter is hard, for example if it came out of the fridge. In this case, it can require a significant amount of force to cut through the slab, and making a straight cut can be difficult. With the tool, you push straight down, so you can use more force. And the right angle shape stabilizes the blade during the cut.