Some argue that one learns by doing, while others argue that we must understand theory first and foremost. And a small group believes that teaching is an art that cannot itself be taught. In some universities, Composition is entirely autonomous. In many places, all three fall within the English Department. Oftentimes this discussion focuses on whether splitting these functions up is a good idea.
Computers cost money.
TA's drain departmental budgets. Hard-core Literature departments don't see the relevance of your interest. You have computers, but you can't get physical plant to come over and lay cables through the floor. This thread on MBU sometimes involves crying on each other's virtual shoulders, but often involves gathering information and formulating strategies to justify a purchase, to increase funding, etc. While we all enjoy teaching, the cold hard facts are that we are laborers, and often require wake-up calls to remind us of that.