There is absolutely no problem visiting Japan. Of course there are certain things to acknowledge to make the stay enjoyable. Personally I believe that the most important thing is to understand that fallout does not respect distances from the source. There are dangerous levels as far as Fukushima city, some 60km from the Dai-ichi, and quite safe areas within 10 kilometers. Stationary government radiation measurements measure average dose from decades ago, so it will take years and years until they get up to speed with the present situation. Instead,
Safecast is doing a rather good job.
There have been instances of obviously doctored data from food inspections, and many food producers and local officials have no problem giving the dangerously contaminated food to schools with the premise that "it's ok as long as nobody knows". I support local economy as much as I can (the latest buy being the
Pocket Geiger counter "Made in Ishinomaki"), but not when it sends the wrong message. I do believe they'll get the message in ten years or so, but it won't do any good, because it will be of the type "nyannyan, told you so".
Also, the free tickets to foreigners plan was published along with the plan to increase retirement age. These are often connected in angry comments all over the net, so if you get a free ticket, it might be a good idea to keep it to yourself while in here.
Japan is much better experience as long as you keep realism in your head.