Holds true here. Selling an idea to a client can be sticky business. Companies need proposals in order to encapsulate complicated projects into simple categories. This helps them understand the full ramifications of what they are getting into. This, to me, is acceptable.
Proposals also help company representatives feel that designers have their shit together.
Realizing that most managers are in-tune with what their peers are proposing, proposals form the contract between the outside programmer and these many internal departments.