This website explains why two-choice party voting would be useful in reducing the negative impacts of the MMP threshold.
Some people have said to me in response to this suggestion, that it would be better to abolish the threshold than to introduce two-choice party voting.
Introducing two-choice party voting has two important and related advantages over reducing or abolishing the threshold. The first is that there is no consensus about whether or how far to reduce the threshold. The second is that two-choice party voting improves the system for everyone, so consensus may be more achievable.
Two-choice party voting may in fact also make the threshold more acceptable to its critics, because many of the problems attributed to the threshold, are in reality the result of wasted votes, that is as a result of the lack of a second choice of party vote.
Two-choice party voting offers some important advantages over any reduction in the threshold short of abolition. Two choice party voting allows every voter to have a say in the overall result of the election, even if they vote first choice for a tiny party with no hope of passing the threshold.
A second great advantage of two-choice party voting is that it allows like minded parties to work together instead of at odds. No longer do potential support parties take votes away from their natural allies.
New Zealand could usefully adopt two-choice party voting as a consensus measure to alleviate the negative effects of the present threshold, leaving changes to the size of the threshold until after some experience of two-choice party voting.