The paper Phil is discussing here reports most of their results in CGS units. It's a good point, though. In my observation, astronomers seem to be more inclined to use CGS instead of SI, as compared to many other areas of physics. Probably this is due to historical precedent, i.e., habit. Theorists often prefer to use 'natural' units in which the speed of light and Planck's constant are equal to unity. In general, as long as you're clear about your units, nobody seems to mind. Converting among different unit systems is supposed to be a basic skill for physicists, although it doesn't seem to ever be taught in any unified way in any one particular class. I guess mostly it's learned by osmosis.