Just pointing out a bit of inconsistency in that argument, although I do hear what you are saying about the decade with the All Blacks, but a coach is not going to get much of the plaudits for performance when they are the assistant coach. You can't take the fact that both coach have been incredibly successful away from them though.
On the topic of who deserved the coach of the year, I think the right man won. Hansen has done an amazing job and has prepared a great team and has performed consistently over the past four years, which is why he won the award three years in a row from 2012-2014. However, if you are looking at the two coaches, (as a neutral to the two teams), you have to have more respect for what Cheika has managed to do this year in comparison to Hansen. Yes, Hansen did win the World Cup, but I feel that a fair amount of that was due to the good work he has put in over the past four years and the strong chemistry he built into the team. Cheika took a team that looked like it was going nowhere this world cup to win their first rugby championship and finalists in a World Cup.