I don't mind the delay, and I like the spectacle, but I don't think that it's necessarily very equitable.
The HAKA is used by the team doing it to intimidate the other team, but more importantly, to fire themselves up. There was a thread posted on here recently about the positive effects that celebrating a try/goal etc has on team performance. It's apprently quite measurable and successful celebrations have characteristics that they have been able to detirmine as most effective. Something like the Haka ticks all of those boxes.
It is therefore entirely reasonable to argue that it provides a team with an unfair advantage, particularly when it forms a key part of the build up and is featured in the way it is with the opposing team unable to turn their backs and ignore it etc. Not only are they ALLOWED to perform the Haka, but the other team is basically FORCED to watch.
Let them do a Haka for the crowd if they must during their warm up, but when the teams run on, it should be scrupulously fair in terms of even treatment for both teams.