As suggested, changing default does not appear to work on ElCap without SIP disabling, and one would argue that disabling SIP to obtain this feature is totally inappropriate. Why does Apple continue to break every feature it introduces, lol.....
What is not clear from the discussion above is whether once SIP is disabled, whether the solution then requires the default change, and then turning SIP back on ;-)
so -the follow on question is that since the csrutil must be used from recovery mode, can the change in default then be implemented via discovery mode, and will it then stick once the system is changed to csrutil and rebooted?
and, why isn;t there a much much much simpler way to access this wonderful feature?