Group insiders, no matter the group, like exclusiveness because it suggests superiority based on association. Such collective worthiness is especially attractive because it can often be achieved by birthright without any personal effort or accomplishment. Exclusiveness elevates above the normal citizen and imparts a sense of entitlement to general respect and admiration.
Many see no advantage or value to being a part of a group which is open to just anyone. To these ones, exclusive means elite and elite means very valuable. Inclusive means mediocre and collectively below average since those who esteem themselves superior will not stoop to join. That describes perfectly the way the carnal mind works.
Inclusiveness implies a general equality which those who desire to feel superior find offensive. Exclusiveness is the very definition of inequality, so if one espouses equality at all, exclusive institutions are anathema.
The proponents of exclusiveness, those who feel superior, are naturally fearful of freedom because freedom empowers the excluded to break down the barriers of exclusion. Freedom is the natural enemy of those who want to feel superior for any reason- economically, religiously, politically. Freedom is soon followed by urge for inclusion because inclusion is the very essence of being free. Exclusion exists because of barriers and restraints. Restraints are the elements which deny freedom in the first place. Absolute freedom means the total absence of externally administered restraints.