What is the standing of Origami in Japan? Obviously it is more widespread there, but is it a niche hobby or something rather common?
Dude, before origami became popular in the west about 50 years ago, it had a very different standing in Japan. Sharing diagrams with the public used to be uncommon, instead masters would teach a handful selected pupils to pass on their heritage. This changed drastically over the last decades, but it's because of western influence.
It seems to me that most origami is more of a children's hobby, like a brainteaser, in Japan. Of course, the more advanced form is definitely not as common, and seems a lot more like a niche thing like you said.