Every language has dialects, and Japanese is no different. I've heard that since Japanese people are more likely to stay in the same place all their lives, or move to Tokyo for work or education then do a "U-turn" (as the Japanese call it) back to their home prefecture a few years later, the country's dialects are more pronounced than in other countries for this reason. Often dialects are used to add a new dimension to a character in anime, and if you have a group of females in a given show, you can bet there'll be one whose "charm point" is speaking some cute but odd-sounding variant of Japanese. Beyond the major dialects -- rough and comical Osaka-ben, eerily polite Kyoto-ben, Gaelic-sounding Tohoku-ben from Northern Japan -- it's funny to observe the "artificial" dialect of gaijin-ben, the over-inflected Japanese that foreigners are known to speak, which is often used by radio DJs and announcers on TV shows to add a "chic" flavor to their speech.
Nisemonogatari is the anime that will make you appreciate Kyoto-ben.