Neither plastic nor wood has been proven to be reliably more sanitary than the other material when it comes to cutting boards and because bacteria can reside on boards for many hours, many sources recommend using multiple cutting boards, designating each for an individual task to avoid the possibility of transferring bacteria from raw meats to veggies and other foods. A good scrub in hot soapy water or in a very diluted bleach solution should be able to rid a cutting board of the majority of the bacteria lurking on its surface, so having multiple cutting boards is not strictly necessary.
That said, they can help keep you organized in the kitchen – especially if you tend to work with multiple cooks around who compete for boards. And there are many well-designed cutting boards out there that pack a lot more appeal than a plain plastic one. For example, these foodie cutting boards, featuring “faces” of veggies and kitchen utensils, are charming without even being used and make the idea of having a few around that much better.