On the surface, I agree with yout supervisor. It seems that the more the courses focus quantitatively, the less demanding regarding your work experiences (Actually, this was my perception before I was enrolled in one profession-oriented ma program in ths States). Nevertheless, during most of these classes after my enrollment (like multivariate, linear regression, etc), many professors asked us to find out one real dataset to work on during the whole semester. If you already have your interest field + some basic background knowledge in your mind, your job can be more beneficial/efficient to your future work/research (at lease they can answer some of the confusions which troubled you before your enrollment); on the other hand, after one semester, you will find it a waste of time.
Since most profession degree program needs financial investment, why not accumulate at least one or two years of working experience to sharpen your interest field? In this way, your graduate study can be more targetted and worthy of your bucks.......
Good luck!