Why does a university course become defunct? What are some reasons that lead to a university course being no longer offered?

I am thinking in particular about the course "Computational sustainability" or CPSC 530M offered in University of British Columbia.

I am guessing the following could be the reasons, but I'm not sure:


Not enough students are interested in the course
The course spends too much money and earns too little
The subject matter is obsolete (e.g. Eugenics theory)
Some reasons we've eliminated courses in my department:


The professor who created the course is no longer at the college or is no longer interested in the material.
College-wide requirements have changed, and the course was created to meet a requirement (such as for interdisciplinary work).
As new courses are added, other courses have to be removed, unless the size of the faculty grows.