I think the Japanese knife is at one pole of the fundamental user interface dilemma: to what extent do you cater to common actions at the expense of expert actions? The Japanese knife says that any concession made to one specific use will unacceptably hinder other uses.

The German knife is specialized for one particular hand position. In a way, it is actually prescriptive and restrictive: if you try to use it a different way than expected, you will have an inferior experience. The designers (hopefully) studied usage and decided that they could optimize for the common case without hindering other cases too much, thereby getting a better result. It doesn't matter if uncommon cases are a little awkward.

It's just common sense that the optimum design will reject the do-nothing approach and provide some kind of non-use-agnostic tweak. However, ten years of software development work have given me much more appreciation for the assumption embodied in the Japanese knife. It's pessimistic and will never be the best (except in the eyes of design gurus who never actually use stuff) but by god it will never stop you from doing what you want.