It wasn't done in the same bills related to Christchurch. Rather, during the 'overtime' to deal with the aftermath of the Christchurch quake, this bill was promoted quickly also.

Doing this speeds up the process and avoids a huge amount of oversight, consideration and public input, and has very much caught the NZ public by surprise.

It's unlikely we (NZ public) will get organised enough to change this, and past laws with significant public outcry (which this doesn't have yet) have stayed without review, as referendum's are not binding in NZ.