The reason to be on Google+ isn’t because it’s the newest, hottest, sexiest thing. That might be a good reason to be on it as an individual (hard to separate) but not why you should be on it as a journalist. You should be on these sites to understand how people are communicating and the vocabulary of this communication. Friendster informed MySpace which informed Facebook which informed Google+.
If you ignore these sites, you will fail to understand how a growing portion of the population deals with the flow of information, and inevitably how more people will deal with this flow in the future. The best journalists will be problem solvers on the social web.
If you are a journalist your JOB is to understand and insert yourself into the flow of information. That’s what Google+ represents, the flow of information.