In graduate school, for special topics class there were usually only 1 or 2 professors that COULD teach a certain class (and only 3 or 4 students interested in taking it)- so when you are talking cutting edge research topics, its a necessity to have a researcher because no one else will be familiar enough with whats going on in the field.

Outside of that, not really. Good teaching takes work, so if you put someone in front of the class whose career advancement requires spending all their time on research, then the teaching is just a potentially career destroying distraction. Also, at the intro level, subject-pedagogy experts tend to do better (i.e. the physics education group were measurably more effective at teaching physics than other physics groups. So much so that I think now they exclusively teach the large physics courses for engineers)

I mean, it's easier to get research positions with those professors, and those are learning experiences, but the students generally get very little out of it during the actual class.