If you make the place too restrictive then people don't feel they can express their views and opinions openly. Diversity occurs naturally when the board has a feeling of openness. People feel welcome to express themselves with out the fear of offending someone because of their opposing views on the subject at hand. It can't be a free for all but limits that are broad enough so members don't feel they have a Catholic Nun standing over them with ruler just trying to find a reason to crack their knuckles.
