I beleive a lot of live albums were originally intended for the Japanese market only (Whitesnake's "Live In the Heart of The City" for instance). Back in the days, I guess it was exotic to go to Japan where every band and their mother were popular (remember the joke: we are big in Japan though!) and there was a huge demand for products.

Japanese fans are loyal, and still welcome "older" bands. I guess it would make sense to record in Japan, mostly for bands that do not really tour much and for which Japan is still an important market.