New Japan is far more geared for technical and mat style wrestling whereas the WWE / WWF is more into the high risk – high flying style of wrestling which is the principal reason why Vince McMahon is losing wrestlers to either long term injury or early retirement.
The WWE is having trouble filling their pay-per-view cards with quality high price matches due to the injury rates of its star personalities not being able to compete for extended periods of time.
New Japan wrestles a more contemporary style and a lot more conducive to its long-term health of its superstars.
Years ago, wrestling superstars such as Dusty Rhodes, Ric Flair, Roddy Piper would travel back and forth to Japan quite frequently. The NWA was working with New Japan creating quite the war between the WWF which escalated into the infamous “Monday Night Wars when the NWA became WCW which unfortunately for the future of professional wrestling, was won by Vince McMahon and the WWF.
The bottom line, Japanese wrestling is a far better product over time and increases the careers of many of its too-name performers.
Just a side note, the “Lucador” Mexican style of wrestling is where the WWE got its inspirations for what they program today. The Mexico wrestling style is far more crowd-pleasing but their wrestlers are much smaller in the frame and can absorb the hits from all the high flying moves. The WWE abused this theory when they adopted this philosophy but their wrestlers are much bigger, less agile, and prone to steroid use leading to the careers of such superstars like Shawn Michael’s, Edge, and CM Punk.
Vince McMahon is his own worst enemy when it comes to the production he gets out of his slabs of meat he calls his superstars.
The main reason guys like Piper and Flair wrestled well into their 50’s was they wrestled mostly for the NWA and WCW. Crockett and Jim Heard were much more conscious of its wrestler’s health and long-term abilities than the evil Vince McMahon ever was.
Source: Quora