What could happen to make you think Kvesic is better than Robshaw or Wood that Kvesic actually has the power to decide? Basically you need one of the former to lose form before Kvesic gets a look in. We won't know how Kvesic performs in comparison to Robshaw/Wood without actually giving him a go. For all we know Kvesic could fit perfectly into the England team and strengthen our pack, which is already capable of worrying pretty much any other pack in the world.
It's as I said about England post 2003, the mentality was that we already had very good players in all positions so why try out new people? Because that first team may not always be available and you need to have backups and replacements. You talked about NZ having a strong team so they could feed players in, we did as well but the difference between us and NZ is we never fed new talent in. The result is that when much of the 2003 team left, England came crashing down. We are now doing exactly the same with our pack. They are good therefore there is no point in letting non-established players try. If we maintain this mentality then I guarentee that we will be screwing ourselves in the future when our current pack starts leaving and we have no alternatives because they never got any game time.