There are roads, railways and bridges across the country. That type of infrastructure won't be back up and running in a day or two. Some Prefectures still don't have power from the previous typhoon last month.
The geography of Japan means that most of the venues have been directly affected. Sapporo? No can do, there's a baseball game on this weekend/week. Fukuoka? Possibly but getting thousands of ticketed spectators there would be an issue.
I don't give a f**k if you think I'm advertising that I live in Japan. I've never made any secret of it but take it from someone with firsthand experience of the daily threat of typhoons, earthquakes and tsunamis, it takes more than a few days to get things back up and running.