I understand your point and I agree that software could make or break a company. That can be true and you could still make the argument that IT is strictly a cost. That IT departments can enable other departments to reduce their own costs does not change the fact that IT itself is a cost.

In your customer service example IT has clearly had a positive impact, but you'd be hard pressed to convince anyone that the IT department is generating revenue for the company. If you walked into the CFO's office trying to make that case you'd be laughed out of the room. Good customer service does not manifest itself through good software.

A better approach may be to walk into the CFO's office and show how your IT department is helping the company realize it's goal of providing good customer service at an acceptable cost. It's a very subtle distinction. This is what I was getting at when I said not thinking of IT as a cost can be a roadblock to advancement.