You can take this with a grain of salt. In a previous company, the corporate management conducted "vision" seminars with the entire supervision/management staff. The attempt was to brainwash.., uh uh, I mean to cast the corporate vision statement throughout the organization. In the seminar, the business consultants that lead the discussion mentioned the power of having a vision statement. They mentioned that a study was performed involving three groups of companies: 1) companies who had no vision statement, 2) companies who had a vision statement, but didn't live it, 3) companies who had a vision statement and lived it out in the daily operation of the business. The results of the study indicated the group 1 companies only had marginal growth of their business, Group 2 companies had moderate growth, but Group 3 companies has substantial growth.
I believe that it is important to have a vision statement or quality policy. A statement defines the management's direction, intentions, commitment, etc. As a company grows in size (employee count) it is important keep the herd going in the same direction. A vision statement, well crafted, will provide a common course to plot so everyone is headed in the same direction. But as they say, "the road to **** is paved with good intentions." Of course having a well crafted vision statement will get squashed like a bug, if it is not driven, enforced, supported by the management teams.