I'm an adjunct professor (I still work full-time in the engineering field, but teach part-time) and I can tell you that ~75% of the professors don't want to teach as much as they want to do research. Most of them are only in academia to do research, but they are required to teach a certain number of classes.
At least at our University, it is mostly a thinktank. We publish research and attend symposiums for research and are mostly motivated by the research. The teaching is a byproduct.
This is probably not the case at community colleges and smaller colleges that are mostly pumping out degrees. But large universities are mostly motivated by research and getting published. That is largely what motivates high quality professors to work there.
