I personally don't have an issue with the back-office clear out when a coach does leave. It's far more important for NZF to have pathways defined for players and coaches to reach elite status. If those pathways are monitored and maintained by NZF staff, provided that each coach appointed buys into them, their job - and that of their assistants - is to coach the team and ensure it is competitive on the field.
Appointing assistants before the main coach is doing it back to front. We're not offering a secure WC spot, good exposure, lots of $ etc - so restricting a potential coach's ability to bring his people with him to a new job is only going to turn away good coaches IMHO.
EDIT: left out a word