The problem is that Japanese Jiu-Jitsu morphed into the modern sport Judo forms in the early to mid 1900s. BJJ was formed from a combat oriented version of jiu jitsu before it became more of a sport than a combat art; it was technically still a part of the newer Judo movement, as Maeda was a part of the Kodokan, but Judo techniques at the same were still the same as jiu-jitsu, only with a different philosophy and sport competition background, and most people still called it jiu-jitsu.
This sport/competition philosophy was the greatest strength of Judo over JJ, but also it's biggest downfall as a legitimate combat art; as Judo became more and more of a sport, it's techniques depended more and more on people who were willing to play the Judo game rather than people from all combat backgrounds, and this watered down many of the techniques. Nowadays, there just really aren't many people who still do JJ out there, and the ones that do are working on techniques from a century ago, while BJJ develops new techniques every year. The art stagnated as sport judo grew, and it's just outdated.
