Now the Japanese, this might look at first like a strange inversion of the principle I keep raising, the white man is apparently compromising his game for what his game represents, while the Japanese are disregarding what is represented for game. Is that what's happening? No. Jshmups are (or were) arcade experiences first. And the arcade is a unique and cultivated sensory experience in itself. Noise, lights, layout, it is all appealing to and competing for your attention. To get you on the game and get you engaged. Arcades are all about stimulation. This influences both the presentation and the form of the games they hosted. Fast, reactive, novel, satisfying and exciting to the senses, these were desired traits. You don't go to the flashing lights and noise club to the bound by gravity. You aren't subject to inertia in the jshmup not because a judgement was made on what would make for the optimal potential complexity in game design. Inertia is out because it is overridden by the rule of cool.
The white man knows he's making a plane-game so he thinks "what is a plane? How does it work? What does it do?" Japanese man knows he's making an arcade game and thinks "what's awesome?" Of course, what the first guy thought would have gotten the ball rolling, each culture referring to its own prior examples. If the first white guy thought "fuck inertia faster is cooler" and the Japanese man thought "horrrr, prane go srow!" maybe things would have gone different. But perhaps the nature of these respective cultures made that highly unlikely from the outset.