That is a good point - especially if an employee who opts out of the scheme actually gets a salary cut insofar as the the employer does not pay the employee the equivalent of what would have been paid into kiwisaver.
Under kiwisaver as it is currently formulated, I think those people who amass a kiwisaver amount that would enable them to buy into a retirement complex would not be in the segment of society that is currently being priced out of freehold home ownership, which they could sell to buy a retirement unit anyway.