Proposals written in strong, clear language are more effective.
Customers may be put off by a message delivered in passive voice in which responsibilities have not been clearly allocated. (See what I did there?)
The active voice construction accepts responsibility, giving the sentence greater clarity, emphasis and credibility.
The most important reason to use active voice in sales documents is to be more convincing and persuasive. Customers want the bidder to accept responsibility, make things happen, appear confident, meet requirements and solve their problems.
Active voice conveys all these attributes.