If you find yourself deeply interested in something you're studying or see something that you want to devote your attention to, then do it. It doesn't actually have to be in a structured academic environment. Now that we've gotten the idealistic stuff out of the way (more and more easily done it seems), the fact of the matter is that a master's degree gives you leverage for better (starting) pay. After a few years at work, however, your performance will determine what you are paid and not your education. I'd say, do it if you have the time/money and you really want to dive deep into something. Otherwise, go and start working.