It depends on the discipline. In the geosciences, MSc degrees are the typical 'working degree'. If you want a job, you basically need one, therefore lots of schools offer them. Most people spend 2-3 years on an MSc and then hopefully get a paper or two out before starting work or going on for a PhD (another 4-8 years). You also have to have a pretty solid thesis to get the MSc so you can't just bow out of a PhD program.

Some of the more academically-focused (private) schools don't have much of an MSc program but they're atypical, and they don't dominate research like they do in other fields.