I certainly don't think we have too many incoming migrants. We need them anyway to balance the departures.
The looming deficit of taxpayers caused by the ageing population is going to create a problem. Increased immigration, especially encouraging foreign students who have studied here to make NZ their home, may be part of a solution.
Frankly, as long as people wanting to come to NZ have a proven work ethic and some usable skills, why turn them away? By developed-world standards, NZ is a sparsely populated nation and looking at the graph below, current levels of migration aren't about to test existing resources.