Okinawan karate has always maintained that it is based on the idea of a civilian self-defense system. The moves are responses to the most common types of attacks.
Japanese karate was introduced to train and prepare young people for military service in Imperial Japan. This is why Japanese training reflects so many aspects of military training. Lining up according to rank, everyone does the same thing done by count etc. They were not concerned with self-defense. If you read about Funakoshi, Gichin he was against the free sparring that became associated with Shotokan. It wasn't until after his death that his son emphasized that aspect.
Because of the roots of Judo and Kendo, Shotokan adopted their one step style sparring based on kendo's use of it and took a close range fighting style based on locks, throws, strikes into a longer distance punching/kicking only art. If you look at older okinawan styles (not talking about them changing their presentation to attract the Japanese) they did more of a flow style sparring/kumite that would have looked more like chinese two person forms.
"God gave you a brain, and it annoys Him greatly when you choose not to use it."