Actually Judo came from Japanese Jiu-Jitsu during the feudal Japan era. Some JJJ moves were too dangerous and deadly, so the emporer commisioned some practioner to create a new fighting system that wouldn't kill it's own people when in training. Judo was the result. I for like Judo and all it's throws, my nephew took Judo for 3 years and he teaches me some stuff. It is not useless to a grappler, not even a striker because if you know the Judo throws and your a striker, then you can counter it.
Gracie Jiu-Jitsu came from both Judo and JJJ, mainly Judo. They just threw out all the moves that needed strength and power and came up with their own system.