One of the reasons Japan has low street crime rates is because these guys are very good enforcers. In the neighborhoods where they’re running businesses or collecting protection money, you won’t see people getting mugged because the yakuza don’t want people to be afraid to come there and spend money. They are a second police force and in that sense, and perform a valuable role in Japanese society.
Interesting tidbit found while crawling the web. Seems like there’s quite a bit of disparity between the yakuza and our local brand of gangsterism.