I just got one, the first time in years, for driving in Italy and Germany. Since I had no problems on the trip, it was unnecesary. It's certainly true that European car rental companies don't require it.

It is required in Japan to rent a car. Still, if you are determined enough, you might be able to rent a car in Japan without it -- I did once.

Although it's cheap -- $15 and two pictures -- it's only good for a year, which is annoyingly short. AAA will issue it for you even if you aren't a member.