I lived in Japan for a year (and I'm actually just about to go back for at least another year!). Over there, there's a really strong 'shoes off' culture, to the extent that many restaurants (especially more traditional Japanese places), karaoke places, some doctors' offices, and many other indoor public places require shoes off and have communal slippers for you to change into. In people's homes there are always little areas when you open the door where you change out of your shoes before entering and change into slippers. They even have different slippers for the bathroom to avoid cross-contamination if you go to the loo.
Now that I'm in the UK, I always take my shoes off in my flat. It's just a nice tradition and keeps outside muck out of the home.