First, buying NOAH and then rebranding as NXT Japan is a huge fucking insult to guys like Misawa, Kobyashi, Kawada, Jun, Marufuji, KENTA, and so many more. As they, mainly Misawa, Kobyashi, and others, made it after leaving All Japan, which took guts to do, and WWE would erase all its history more than likely and even try to change the style of wrestling, which is just an insult as well. NOAH is the last promotion that still teaches King Road Style, a style is that pretty much nonexisting nowadays.
Second, WWE is a niche company in Japan when compared to New Japan, All Japan, DDT-Pro, Dragon Gate, NOAH, Michinoku Pro, and so on. That is why you never see WWE run a show over there when one of them is running a show as many would go to one of the companies I mentioned over WWE.
Third, WWE has to understand you can't fucking capitalize on Wrestling everywhere it isn't going to happen. Japan has deep roots and so does Mexico with Lucha, and no matter what you aren't uprooting them. You can in the UK because it was like the Wild West out there, so NXT UK made some sense.
Fourth, Japanese wrestlers tend to have loyalty to the company that gave them their break and such. So trying to get some of the top guys to join NXT Japan wouldn't go so well, but I know there some exceptions but generally speaking it wouldn't go over so well.
Fifth, look at the talent WWE has from Japan. Shinsuke Nakamura, Asuka, Kairi Sane, Io Shirai, Akira Tozawa, and Kushidia all of them are highly talented wrestlers, but once they came to WWE well...they barely shined or did anything of any importance and that is a damn shame. Granted, you can say that Shinsuke and Asuka and even Kairi Sane had good moments/feuds, but they were meaningless. So even if NXT Japan was a thing they soon come to NXT and be a face for a while, but guess what happens after that...they turn heel because every foreigner has to be a fucking heel. God forbid for one to be a face.
Finally, it would "ruin" everything great about Japanese wrestling form the stories to the feuds and so on. Americanized version of Strong Style or even King's Road isn't that entertaining, just look at Omega and I say that as a fan of his. It is kind of fun and can put on good matches, but it isn't what Japan is all about. It would get rid of the idea of the heroic face and the fighting spirit concept that is loved in Japan. I am glad that NOAH denied it, and I hope NXT Japan is just a pipe dream and it never comes true. Also, some of the wrestler's gimmicks wouldn't work well in both the American style of wrestling and they wouldn't connect to an American audience, an example being Shinsuke being the King of Strong Style or Kairi Sane being a "pirate" or Io being called The Genius of the Sky none of it connected or anything and WWE barely did anything to make people connect it, but still.
All in all, I am glad NOAH refused to sell and make me love the company more. Also, impressed no one tagged me.