According to Rashi the death of Nadav and Avihu was (as earlier to to Moshe by G-D) in order to sanctify the Mishkan. So in a sense the sanctification of the Mishkan (i.e. G-D's indwelling within it) required human sacrifice.
Is there a a reason for this human sacrifice given? Or a precedent of human sacrifice for a holiness to manifest?
(Note: this is just according to Rashi.)